by KetoDietApp.com
Step 1Make the cake base. Line your slow cooker with parchment paper and turn the heat to low. In a bowl, using a hand whisk, mix the wet ingredients for the cake base: eggs, melted butter and lukewarm almond milk (also apple cider vinegar if you are using it instead of cream of tartar).
Note: For oven baking instructions, see recipe tips above.
Step 2Place all the dry ingredients for the cake in a mixer: almond flour, coconut flour, whey protein powder, granulated Erythritol, baking soda, cream of tartar and salt. Mix until well combined. Pour the egg mixture into the mixer and process until smooth.
Step 3Pour the batter into the lined slow cooker and cover with a lid. Cook on low for 2 to 3 hours (until the top is set). When done, remove the lid and let the cake cool down until it reaches room temperature.
Step 4Meanwhile, prepare the coffee-rum custard filling. Place the egg yolks in a bowl. Add the Erythritol and whisk until frothy.
Don't waste the egg whites and use them in other recipes. You can find tips on how to use leftover egg whites in this post: Keto Lemon Curd.
Step 5Pour the almond milk, cream and coffee into a saucepan. Bring to a simmer. Use a ladle to gradually temper the hot coffee mixture into the egg yolk and Erythritol mixture. When you have added about half of the coffee mixture, return everything into the saucepan with the remaining almond and cream mixture and cook until it reaches 70 °C/ 160 °F (this will take 6-8 minutes).
Step 6Sprinkle gelatine powder in a bowl with 2 tablespoons of water and combine until dissolved. Then, add it to the saucepan and mix well.
Step 7Take off the heat. Add the rum and optionally, a few drops of stevia to taste. Pour the custard in a glass bowl and cover with a cling film. Chill for 2 hours before pouring on top of the cake.
Step 8Using the handle of a wooden spoon, poke several holes all over the cake base. Pour the custard all over the cake base until covered and the holes are filled. Set aside. I left in a cool place for 2 hours to help the custard cool down and set.
Step 9Meanwhile, prepare the mascarpone topping. Separate the egg yolks from the egg whites. Place the egg yolks into a heat-resistant bowl. Beat with a tablespoon of water, and add vanilla extract and powdered Erythritol. Beat until pale and creamy.
Step 10Place the bowl on top of a saucepan with simmering water. Cook for about 10 minutes, stirring constantly. Remove from the heat and continue stirring to cool. Fold in the mascarpone cheese.
Step 11Whisk the egg whites with a pinch of salt until it forms stiff peaks. Using a large spoon, slowly fold in the whisked egg whites, adding them in two parts to keep them as fluffy as possible. Spoon and spread on top of the cake.
Step 12Finish with an even sprinkle of cacao powder. Grab the parchment paper with both hands and transfer the cake into the fridge to chill until set. It is important to use firm parchment paper that doesn't tear (e.g. parchment paper lined with aluminium foil on one side).
Step 13Once chilled and set, slice into 13 pieces as pictured below. Enjoy!
Step 14Store in the fridge for up to 5 days. If you don't have a slow cooker, follow the instructions in this recipe for oven balking: Keto Key Lime Poke Cake.