Preheat the oven to 190°C and grease a loaf pan or other form
Whisk egg whites and salt until stiff, add sugar and cream tartar with a hand mixer.
Scrap the vanilla bean half and add the vanilla, the almond flour and the bitter almond drops slowly by hand.
Divide the fluffy dough into 4 different bowls and add to any one edible color. Mix slowly in. Now put one colored mixture after the other into the baking form. Remember that the cake will be upside down later, so start with the color you want on the top. Take a fork and mix carefully the dough to get the colors mixed up.
Transfer into oven and bake it for half an hour. Have a look already after 25 minutes.
Take the baking form out of the oven and turn it upside down on a cake dish. It will cool out and slowly set.
You like you can put some icing sugar or glaze. Or serve with some coconut cream. What do you think about ice cream? Or a chocolate glaze.