In the bowl of an electric mixer, beat egg whites till stiff. Slowly add sugar. Add cocoa and margarine and mix until well combined. You will need to scrape the sides of the bowl to incorporate. (Make sure to mix on low before raising the speed up to avoid dusting your kitchen with cocoa.)

Preheat oven to 350 degrees Fahrenheit. Grease loaf pans.

Once dough is ready, flour your working surface and roll dough into a thin rectangle (I like to roll on a silicone mat). Brush the surface with some of the egg yolks, then smear the filling on the dough, making sure to leave a one-inch border all around.

Roll up jelly-roll style, pulling back as you roll to get the most layers possible.

Twist into a figure 8 and lay in a loaf pan. Repeat with remaining dough.

Wash with remaining egg yolk and top with crumbs.

Let rise for 30 minutes.

Bake for 35 minutes.