Preheat oven to 340F (170C). Grease and line bottom and sides of a 9 inch (23cm) pan with parchment paper.
Separate egg whites from yolks. Add a pinch of salt over the whites and start mixing until foamy. Gradually add sugar and continue whipping until stiff peaks form.
In a small bowl mix egg yolks with almond extract and fold them into the whipped whites.
Gradually add ground almonds and flour and carefully incorporate into the batter.
Pour the batter into the prepared pan.
Bake for 40-45 minutes until lightly golden.
Let it cool for about 10-15 minutes. Remove from pan and cool completely on a rack.
Meanwhile prepare the frosting. Place chocolate and coconut milk in a heatproof bowl and let it melt over a pan with simmering water.
In a large bowl mix Mascarpone cheese until smooth. Add melted chocolate and mix until combined.
In another large bowl whip the cream until stiff peaks form. Incorporate powdered sugar and coconut extract.
Gradually incorporate whipped cream into the white chocolate mixture. Fold in the shredded coconut. Cover and refrigerate until ready to use.
Assemble the cake. Divide the sponge cake in 3 layers. Place one cake layer on your serving plate.
Spread ⅓ cup coconut milk over the cake layer. Spread evenly with a bit less than a third of frosting. Repeat with the second layer of cake. Add the third layer of cake and spread with the last ⅓ cup of coconut milk. Spread the remaining frosting on top and sides of the cake.
Sprinkle shredded coconut on the top and sides of the cake and refrigerate until ready to serve.