• The MasterChef Australia 2020 recap collection: we watch the show so you don't have to

It's immunity challenge night, but let's not pretend we care who wins tonight. The reason why we are all really watching is that for months Channel 10 has been promising that Katy Perry will come swooping in as a guest judge, and tonight is finally the night! After 12 years and probably millions of royalty money from Hot N Cold being the ever-present MasterChef theme song, the international superstar is finally acknowledging the show's existence.

After yesterday's Mystery Box challenge saw a twist within a twist within a twist throw the contestants off their cook, Poh, Reynold, Reece, Sarah Tiong and Simon won the chance to cook for immunity, totally unaware that today's twist will be probably the most famous person that's ever graced the show. Yeah, Gordon Ramsay, I said it.

Melissa tells them that they can cook anything they want but it must be "hot". She clarifies that she means temperature "hot" not spicy "hot", but doesn't specify if it also means Hemsworth brothers "hot" so I guess that will just be up to the contestants' interpretation.

Andy gives away one of the twists now: the hot dish must also have a cold element in it, too. Reynold puts two and two together and starts figuring out the connection to the theme song. Andy mentions that there will be another twist coming, but they won't find out what it is until later. (It's Katy.)

Reece has decided to make a hot rum baba cake served with a cold smoked honey cream. He starts making the dough so it has time to prove in the oven, then researches his syrup by doing rum shots. This is also how I like to conduct research of any kind.

Sarah thinks a dessert is too easy for this challenge so is braising some pork and serving it with granita. Not sure if Sarah has been paying attention to Reynold's desserts, because they never look easy to me. Today he is making a matcha genoise (which is a Reynold way of saying a green tea sponge cake) with a yoghurt sorbet and a million other elements I can't keep track of. He says he will be working down to the last second and is "going to Poh it", which shows what a bad influence Poh has been on all of us.

Poh admits she has had another Poh-llercoaster week. She wants to win so plans to bring her Malaysian heritage out. She also tells the judges she's going to bring out "crazy Poh" today so we had all better get our peppermint tea ready. She says her duck rendang dish has about 35 ingredients, which rings about 35 alarm bells in my head.

Simon the vegetarian is making a strange hot carrot circle with a cold parmesan custard. Melissa says it sounds good, but I think she is just practicing her diplomacy for when Katy arrives.

Which is now. Jock calls #TwistTime! He says the second twist is not a new ingredient, but a guest judge. The gantry all start whispering about what this means.

And there she is. I don't know how Channel 10 actually managed to do it, but in walks a very pregnant Katy Perry in an amazing skin-tight orange leather dress. I can tell you right now that when I am pregnant, all of my many skin-tight leather dresses are going straight to the Vinnies' bin.

Katy hugs Poh. Reece starts having a conniption. Simon awkwardly touches her hand like he is about to kiss it, but then realises that would be creepy. Poh goes from crazy Poh to hyperventilating crazy Poh. Sarah is so starstruck she forgets to stir her onions.

Katy announces that they will now be cooking for five, her and her unborn child.

Reece forgets his basic adult functions – he can't talk, he stops breathing. Maybe he is dying? He crouches down and looks like he might stick his head in the oven. Hold it together man!

Katy looks less than impressed with Simon's vegetarian dish and just winks and says "condiments" multiple times. Simon pretends to know what she's talking about, but truthfully no one knows what she means.

Katy visits Sarah, who is absolutely fangirling. Katy keeps saying she is "with child" like a massive weirdo instead of just pregnant like a normal person. We get it, you're famous.

She loves the idea of Sarah's pork dish because she "loves a sweet meat". Jock has lost control of her and she keeps staring into the camera like she's Fleabag. The gantry break into a terrible rendition of Hot N Cold.

Jock and Katy visit Poh and her spicy duck rendang. Jock says that Katy has been craving spicy food since she has been "with child" and WTF – was this part of Katy's contract for being on the show?

Finally Katy starts singing Hot N Cold, which is what we have all been waiting for, but embarrassingly no one joins except for Hayden. They start harmonising, and by harmonising, I mean the opposite of that.

Reece keeps having to take time outs by the fridge so he can gather his thoughts.

Katy wants to have a tour of the pantry because she is a Famous Person and has never been to a supermarket before. She is amazed by all the things and wishes she could have it all… which she most definitely could because surely she is so rich she takes baths in tubs filled with $100 bills?

Melissa gives Katy a bottle of HP sauce as a souvenir forgetting that Vegemite exists.

Reece runs into the pantry pretending to get another ingredient, but really we all know it's just so he can sniff Katy's hair. He says that because she is pregnant ("WITH CHILD") he will make a vanilla syrup to soak Katy's cake in so she doesn't have to drink the rum. To be honest, Katy is bouncing off the walls like she skulled four Long Island ice teas before she got out of the car.

Katy rightly points out that Simon is cooking about three slivers of carrot and that is not going to be enough to feed three judges and a hungry cranky pregnant woman. Simon doesn't really know how to respond to this so just smiles and nods.

On the other hand, Katy is very happy with Sarah's abundance of pork in her dish. She keeps flirting with Sarah and touching her and whispering in her ear. We all know she has kissed a girl and liked it, so I am very excited for Sarah's prospects.

Katy has a taste of Poh's spicy duck rendang and almost catches alight from the spice. She starts coughing, her eyes start watering and her nose is running. She has an actual diva moment where Melissa has to request a glass of water from the crew, but also she should probably be tested for Coronavirus.

Katy whispers "10 minutes to go" in Sarah's ear like a right tease. She sings to Poh about almost killing her. I cannot handle the chaos of this episode.

And things are not going well for Reynold, his yoghurt sorbet is icy and he has overcooked his matcha sponge cake. Katy tastes it and sings to him... if she is going to make all of her judgments via song, I'm out.

Katy makes up a song about there being five minutes to go and everyone loses it.

Two minutes to go and Reynold is still making elements which is very unlike Reynold but he was trying to channel Poh for this challenge. Khanh says "I like your glazed balls" from the gantry, which sounds about right.

Katy yells "one minute!" with such vigour I am worried she may spontaneously give birth.

Poh says that her dish is just as sassy and feisty as Katy, so feels confident. I wasn't aware that a duck curry could be either of those things but I am willing to be proven wrong.

It's time for the judgments and Katy calls over Sarah first. Sarah is extremely excited to be "getting pork onto Katy Perry's fork" and I am wondering if that is a euphemism for something?

Katy suddenly claims to have a sprained thumb and requests that Jock cuts her pork up for her. She also sings "put it in my mouth daddy" and this is going down a path I did not see coming. As Katy bites in, Sarah starts having a moment and can't control her emotions. Katy also seems pretty aroused by Sarah's pork. The twists just keep coming.

But seriously, Andy is very impressed with the dish. Melissa says it felt effortless. Jock says it's an absolute killer.

Katy calls on Simon next, which may be because his dish is about the size of an amuse bouche. He tells them it is pan-fried carrots with parmesan custard. He lies because there is definitely not multiple carrots on that plate.

Katy requests a "lovebite" from Jock. Unfortunately this is not a hickey (although I definitely feel like Jock could take down Orlando Bloom in a punch up), but just a spoonful of everything. Katy is happy with. Jock says that he has treated the vegetables "with respect", which is what I always look for in a man.

Reynold is next with his matcha yada yada yada apple caramel blah blah almond sable bobbledy boop curd pebbles. Katy says she is lost in Reynold's world of matcha. But when she has a bite she says there are "so many different tastes". Nobody seems to like it all that much. Katy hopes Reynold doesn't burn her records, but I'm pretty sure everyone stopped buying actual records 12 years ago.

Poh brings over her dish next, a pass-the-parcel of duck rendang covered in turmeric sticky rice covered in pandan crepe and served with a cucumber relish. Katy says it looks like a Malaysian burrito.

Katy says that because she is a basic b---, she was worried about the duck. But she goes in for more and even eats the rest of the judges' portions. Jock says it has attitude and Katy starts gently twerking in delight making that leather dress work hard. Melissa says this is a "magical Poh moment". I love Melissa, but "magic" is to her what "banging" is to Andy. New adjective please.

Reece is last with his rum baba, which looks yum but also like something you might get at an office bake sale. Katy says in a polite way that it is not as fancy looking as Reynold's but she still thinks it will "hit her spot". Not sure if Reece is qualified to do that though…

As she takes a bite, Katy starts doing an interpretive dance. Melissa hoes in with her hands.

Then Katy starts mysteriously folding up the napkins like she's going to make those weird folded serviette chickens you used to make as a kid (at least I did). But she ends up making the napkins into a pair of breasts, which I am delighted to know is a thing, and says, "you're the tits, Reece". This may be the best thing that has ever happened to Reece, and also the best thing to have ever happened on this show.

The judges start deliberating. Katy nominates Poh's and Sarah's as her favourite. All her judgements are actually pretty spot on, she thinks Reece's was delicious but a little basic for the competition, and while Reynold's looked good, the taste didn't live up to its beauty. Can I just say out to the ether that Poh's cold element was a bit of a joke. Like it was just chopped up cucumber that she put in the fridge before serving, not a handmade sorbet or cream or granita… But anyway, no one cares what I think, do they?

Katy announces the winner and it's Poh! Katy says that she has never ordered duck before but Poh has changed her mind forever. Crazy Poh out here changing lives, people! Katy says thank you to the contestants, and also to Channel 10, whose 12 years of royalty payments have really helped with the extensions on her beach house in Malibu. Byeeeee.

But also:

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