Lemon Sponge Cake

1.   For best results, weigh the ingredients either in grams or ounces

2.   Place rack at bottom third of the oven and preheat to 150 C or 300 F

3.   Line the bottom and side spring of a 15 cm (6 inch) spring form cake pan with parchment. Use butter on the sides to help keep the parchment in place

4.   Separate the eggs, placing whites into mixer bowl and yolks into a small bowl

5.   Whip the egg whites until they start frothing, add the white vinegar, and continue whipping until soft peaks form

6.   Slowly add the sweetener, 1 tbsp at a time, to egg whites, incorporating each tablespoon before adding more sweetener (allowing a few seconds between additions)

7.   Continue whipping until the medium stiffness stage then

8.   Add the egg yolks, using a hand whisk. Gently whisk the yolks into the whipped whites until the mixture is a uniform pale yellow

9.   In a bowl, combine the coconut flour, almond flour and salt. Stir

10.   Using a fine mesh strainer, add 1/3 of the flour mix and combine using a balloon whisk, before adding the second and third amounts

11.   In a glass or measuring cup, combine the oil or melted butter, lemon juice and lemon rind. Stir and pour slowly into whipped egg mixture while blending gently with a spatula

12.   Pour into parchment-lined (bottom and sides) 15 cm (6 inch) spring form pan. Run a knife through to remove large air pockets and then drop/tap to eliminate small air pockets

13.   Bake for 35 minutes then test with a toothpick it to see if done. If not done, continue baking for 5 minute intervals until the toothpick comes out clean. Then increase the oven temperature to 170 C or 340 F for 3 minutes to make the top golden

14.   Remove from oven and place on counter to cool down. When cake is at room temperature, loosen the spring and remove the rim. Gently peel off the side parchment. With the use of a wire rack or second plate, flip the cake and remove the bottom parchment liner, then again flip the cake back upright

15.   Place the cake into the refrigerator for several hours until the cake is completely chilled

Mascarpone Whipped Cream Frosting

16.   In a mixing bowl, add the mascarpone and the sweetener and whisk at low speed for 1 minute until well-combined

17.   Add the whipping cream and mix at low speed for about 30 seconds, then increase the speed to high and whip until stiff peaks form. Cover the bowl with cling wrap and place in the refrigerator until ready to use

Frosting the cake

18.   When the cake is completely cooled, remove from fridge and cut into half (top and bottom). Carefully remove the top layer – use support when removing the top layer so that it does not crack. Set aside

19.   Place bottom half of the cake back into the spring-form pan before piping the mascarpone whipped cream frosting on top of the cut section

20.   Using a piping bag and starting in the center, move in an outwardly-expanding circular motion, squeezing out a thick layer of frosting right to the edge of the cake

21.   Carefully place the top half of the lemon sponge cake on top of the frosting and then repeat the piping out of frosting to the top of the cake. Repeat until there is frosting that reaches the top rim of the cake pan

22.   Smooth the top surface with an offset spatula or the back of a long knife

23.   Run a spatula or small knife on the inside of the pan rim, to loosen the frosting from the spring-form pan before you remove it

24.   Gently and carefully remove the side of the pan

25.   With a spatula, apply frosting to the side the cake. Smooth as well as you can

26.   Refrigerate to allow the mascarpone whipped cream frosting to set before cutting and serving. Take out of fridge just before decorating and serving. Cut into 8 pieces

27.   OPTIONAL: What you use to decorate the top is up to you. Fresh fruit such as thinly-sliced strawberries are both attractive and complement the lemon freshness and mascarpone whipped cream frosting. Alternatively, use lemon peel ribbons, or make swirls with some of the frosting.

28.   Enjoy!