Lemon Curd Swirled Sheet Cake
This lemon sheet cake has a lot of delicious going on! It’s a super easy whole boiled lemon cake, with the added punch of a tangy lemon curd, in the cake and the cream cheese frosting. And my recipe for lemon curd uses a never-fail method.
Equipment
- 5cm x 25cm x 23cm baking pan
- Medium sized pot
- Food processor or blender
- Stand mixer or hand mixer
- Large disposable piping bag
- Offset spatula
Ingredients
Lemon curd:
- 1 batch Lemon Curd
Whole lemon cake:
- 4 large eggs + 1 yolk (room temperature)
- 1 ½ teaspoon vanilla essence
- 450 g white sugar
- 415 g all-purpose flour
- 18 g baking powder (1 tablespoon + ¾ teaspoon)
- ¾ teaspoon salt
- 150 g unsalted butter (room temperature)
- 150 g Greek full fat yoghurt (room temperature)
- 450 g whole lemons (4 medium lemons)
Vanilla cream cheese frosting:
- 250 g Philadelphia original cream cheese
- 155 g unsalted butter
- 415 g pure icing sugar
- ¼ teaspoon salt
- 1 vanilla bean (or 2 teaspoons vanilla essence)
Instructions
Preparing the lemons:
- Wash whole lemons and place in a tight-fitting pan and cover with cold water.
- Cut a piece of baking paper slightly larger than the pan, crumple it up, smooth a bit and tuck it over the lemons with any extra paper facing upwards.
- Place a heat proof bowl on the baking paper to weigh the lemons down. You want them entirely submerged.
- Bring to boil slowly and then reduce to low so that the water is just simmering. If you boil the lemons too vigorously they will split open and lose all their juice.
- Simmer 40 - 50 minutes until the lemons are soft and the skin indents easily if you prod it.
- Gently transfer lemons to a plate cool to room temperature. Discard cooking water.
- Meanwhile preheat the oven to 155°C fan forced (175°C conventional).
- Break up the lemons, removing all seeds and the toughest central pith.
- Process in a food processor or blender, scraping down as you go. You want as pretty smooth puree with no big chunks of peel.
- Measure out 320g of pureed lemon and discard any leftover puree.
Making the cake:
- Prepare the baking pan (see notes).
- Sift the flour, baking powder and salt into a small bowl.
- In the bowl of the stand mixer add the butter and sugar. Beat on medium high until super fluffy and a pale yellow colour. Scrape the bowl down.
- Beat the eggs, yoghurt & vanilla together in a small jug and to the butter and sugar mix slowly on medium speed. Beat until egg fully incorporated and then scrape the bowl down.
- With the mixer on low, add flour in 3 batches, alternating with lemon puree. Mix until just combined each time.
- Then beat the batter on medium speed for a maximum of 30 seconds until batter is fully combined.
- Bake at 155°C fan forced (175°C conventional) for 35-40 minutes. Use a cake tester or skewer and if it comes away with just a few crumbs of cake, it’s done.
Vanilla cream cheese frosting:
- Sift icing sugar and salt into bowl of stand mixer.
- Add cold butter cut into small cubes & beat on medium until a smooth firm paste is formed.
- Split the vanilla bean in half lengthwise and scrape out vanilla seeds. Add the seeds (or vanilla essence) & beat briefly to incorporate on medium.
- Spread the cold cream cheese across a plate in a thin layer. Add it gradually to the bowl while mixing on low. Scrape down the bowl a couple times.
- This method helps to avoid lumps and keep beating on low until there are no lumps.
- Briefly mix for a few seconds on medium to make sure the frosting is completely smooth.
To assemble:
- Using an ice cream scoop or large spoon, deposit the frosting across the sheet cake.
- Smooth into an even layer with an offset spatula.
- Pipe the remaining lemon curd across the frosting in swirls.
- Gently incorporate the curd into the frosting with a small silicone spatula, making sure to not overmix so swirls of icing and curd are clearly visible.
- Decorate as desired.
Just before you cook with abandon…
Make the cake a day ahead. On the day you bake this whole boiled lemon cake it will have a nice tender crumb. But I actually prefer making it a day in advance. After it sits overnight in the fridge, the cake becomes much moister and slightly denser. It’s also a good idea to glaze it after a night in the fridge, as the glaze adheres better to a cold cake. The glaze will absorb into the cake with time, which isn’t an issue as you still get all the flavour. But for presentation you may wish to glaze it just before serving it.
Room temperature: When making cake, all your ingredients should be at room temperature as it ensures that your batter does not split. This increases the chances of you getting a perfectly baked cake. I get the butter and eggs out the night before. And, if I forget, I put the weighed out butter in a warm oven - no higher than 30°C for a few minutes. Set a timer - you don’t want melted butter. And you can put the eggs (shell on) in a bowl and pour hot water over them & they will come to room temperature in a few minutes.
Eggs: Large eggs weigh about 52g each in the shell.
Kitchen scale: If you are going to bake, you need a kitchen scale. It’s really in the necessity column not the optional column. You don’t need to spend a fortune on them, decent ones can be bought for about $70. I find the expensive ones break down just as quickly as the cheaper versions. But I would recommend you go for a known brand from a reputable kitchen shop.
Tablespoons – there are two sizes: Yes, there are two sizes of tablespoons found in recipes. It appears that Australia is the outlier with the bigger version at 20ml. While North Americans (and most countries) measure a tablespoon at 15ml. I use the 15ml version in all my baking recipes where small deviations can change the result dramatically.
Preparing the sheet pan: I use a spray oil or butter to grease the pan well. Then I measure out a length of baking paper to go across the pan lengthwise and up both ends. This ensures that you can always get the cake out of the pan.
Oven temperatures: Cakes are supposed to be baked in a conventional oven (top and bottom heat), as a fan forced oven (convection) dries the cake out. All well and good if your oven maintains an even temperature on that setting, mine does not. I use the fan forced setting on a lower temperature, as this gives me a more even heat distribution in my oven. I don’t believe in oven thermometers as they are notoriously inaccurate. But you will know there’s a problem when two cakes on the same rack (on the conventional setting) bake at very different rates. The only way you can accurately test your oven temperature is with a laser temperature gun (and, yes, I have one!).
Stand mixer versus hand mixer: I love my stand mixer but most batters can be made with a good quality hand mixer. The one exception is kneading bread or pizza dough, the stand mixer doesn’t have enough power to knead dough. If using a hand mixer with my recipes, I recommend generally following the speed instructions. You may need to increase the time you beat the batter a bit before you add the flour. But be careful when incorporating the flour as if you overbeat it you will over activate the gluten and have a much denser cake as a result.
Testing for doneness: Making the cake can feel easy compared to knowing when to open the oven to see if the cake is done. Open it too early and your cake batter will collapse, wait until the cake has pulled away from the sides of the pan and your cake will be overbaked. You want to start testing when the cake is forming is crumb. It’s dense cake, so don’t open the door before 30 minutes. The cake is done when your tester comes out with a few cake crumbs attached. And if you are like me and own a Thermapen, the cake will be done when its internal temperature is 93-94°C.