Keto Lemon Layer Cake

Amy Massey
by Amy Massey
16 Servings
1 hr 45 min

This recipe was a bit of an experiment for a birthday party because the birthday girl was following the Keto diet (low carb, high fat). What really surprised me, as well as all of the other guests, was just how delicious and sweet a cake made without traditional flour and without sugar could actually taste! The sponge cake w as unbelievably light and airy, the flavour of lemon was strong yet not overpowering, sweet without being bitter and the frosting was so sweet and moreish you didn't even know there was no sugar in it!

And its for that reason that I would highly recommend making the switch to a cake like this if you're following a similar diet and watching your waistline, or even if you just want to reduce the amount of sugar the kids are getting but still want to indulge in a slice of cake from time to time!

Served in the countryside for the perfect afternoon tea.

The perfect birthday cake for a keto fan that doesn't want to fall off the wagon!

Light and airy lemon sponge cake is sandwiched together with a homemade lemon curd and freshly whipped cream.

Covered in a sweet cream cheese frosting, it needs no other decoration and the flavours speak for themselves.

Recipe details
  • 16  Servings
  • Prep time: 15 Minutes Cook time: 90 Minutes Total time: 1 hr 45 min
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For the lemon curd
  • 6 large egg yolks
  • 1/2 cup powdered erythritol
  • ½ cup lemon juice
  • 1 tbsp lemon zest, finely grated
  • 3 oz unsalted butter, cubed
For the cake
  • 2⁄3 cup coconut flour
  • ½ cup oat fibre
  • ¼ cup vanilla whey protein
  • 2 tsp baking powder
  • ½ tsp salt
  • 8 oz unsalted butter, softened
  • 2⁄3 cup granulated erythritol
  • 8 large eggs
  • 1 cup heavy whipping cream
  • 2 tsp vanilla extract
  • 2 tbsp lemon juice
  • 2 tbsp lemon zest
  • 5 drops liquid sweetener
For the frosting
  • 2 cups heavy whipping cream
  • 1 cup powdered erythritol
  • 2 tsp vanilla extract
  • 2 cups mascarpone cheese
  • Finely grated zest of 1 lemon
For the lemon curd
Place the lemon zest, lemon juice, sweetener and egg yolks in a small saucepan and whisk over a low heat until it reaches 175 degrees Fahrenheit and begins to thicken.
Gradually add the butter, whisking until incorporated.
Strain through a sieve to remove any lumps.
Set aside and leave to cool while making the cake.
For the frosting
Whip the cream in a large bowl using a hand mixer until soft peaks form.
Gradually sprinkle the sweetener into the cream and continue to whip.
Stir in the lemon zest and refrigerate until ready to frost the cake.
Place one layer of the cake on a cake plate and spread 1/2 of the lemon curd on top.
Lightly cover the lemon curd with a thick layer of mascarpone frosting.
Too with the 2nd layer of cake and cover with the remaining lemon curd.
Spread the frosting over the entire cake evenly, then place in the refrigerator for at least 30 mins until set.
For the cake
Preheat your oven to 350 degrees Fahrenheit.
Grease two 8-inch round cake pans and line with parchment paper.
In a large bowl, combine the coconut flour, whey protein, oat fibre baking powder and salt.
In a separate large bowl, use a hand mixer or stand mixer to whip the butter and granulated sweetener. 
Add the whole eggs one at a time and continue to beat well.
Stir in the heavy cream, vanilla extract, lemon juice, lemon zest, and liquid sweetener by hand.
Add the dry ingredients and mix by hand until just incorporated.
Divide evenly between the two cake pans and bake in the centre of the oven for 25 to 30 mins, until the cakes are cooked in the centre.
Place on a wire rack and leave to cool.