1. Preheat the oven to 160 C or 320 F. Line a 20 cm X 20 cm or 8 inch X 8 inch pan with parchment paper
2. In a bowl, combine all the dry ingredients: the almond flour, coconut flour, baking powder, glucomannan and salt
3. Separate the egg yolks and egg whites into two separate bowls
4. To the bowl with the yolks, add the powdered sweetener and whisk with an electric mixer until pale yellow and frothy. Add the vanilla and the half and half cream mixture and whisk to combine
5. Place a mesh sieve over the bowl with the yolk mixture and add the dry ingredients to the sieve and whisk to aerate. Gently mix to combine the yolk mixture and the dry ingredients. Do not over mix
6. To the bowl with the egg whites, add the lemon juice and whisk at high speed until light and frothy. Gradually, one tablespoon at a time, add the powdered sweetener. Continue whipping until the stiff peak stage
7. Use about 1/3 of the egg whites and fold into the yolk batter mixture. Blend to loosen the yolk batter. Add the remaining whipped egg whites and gently fold into the yolk batter until the white disappears. Do not over mix!
8. Pour the batter into the prepared parchment lined baking sheet. Run a knife or skewer through the batter to remove any large air bubbles, and also, gently, drop the pan onto the surface of your counter a couple of times
9. Place the pan into the middle position of your preheated oven and bake for 25 – 30 minutes. Test with a toothpick and, if done, remove the pan from the oven and let the cake cool in the pan for 20 minutes. Then flip onto a parchment lined cooling rack. Let cool completely. If you want, trim the sides of the cake to make a clean, even edge
10. In a large measuring cup or small mixing bowl, combine the heavy cream, sugar free sweetened condensed milk, and the store bought evaporated milk (or your half and half milk mixture, or the almond milk). Whisk vigorously to combine.
11. When the cake is cooled, place the cake with the parchment liner into a larger cake pan. Poke the surface of the cake with a fork or skewer. Pour the 3 Milk mixture all over the cake. Refrigerate for at least one hour
12. Just before removing the cake from the refrigerator, whip up the frosting. Whip the cream and powdered confectionary sweetener to medium stiffness stage. Add the vanilla and whisk to combine. OPTIONAL: if desired gently whisk in the room temperature mascarpone cheese. Do not over whip
13. Add the cream frosting on top of the cake and smooth out the surface with an offset spatula. Cut the cake into 3 even sections lengthwise and then 3 even sections width wise to make 9 servings. Garnish with berries of your choice. Enjoy!