Time:

Mix and ferment sponge: 2 hours
Mix final dough: 10 minutes
First fermentation : 30 minutes, then 8 – 16 hours in the refrigerator
Divide and shape: 20 minutes
Proof: 3 hours
Bake: 20 minutes
Sponge Ingredients:

113 g flour
3 g instant yeast
1 T. warm water
50 g (one large) egg, lightly beaten
Final Dough Ingredients:

450 g flour
180 g sugar
3 g (1/2 t. salt)
45 g unsalted butter, softened
220 g egg
57 g warm water
7 g instant yeast
all of the sponge
Topping Ingredients:

114 g all-purpose flour
114 g powdered sugar
91 g unsalted butter, at room temperature
Colors/flavors as desired. The original recipe specifies, 2 T. cocoa powder for half, and 1 T. cinnamon for the other half. I divided the dough in quarters and used 1 T. coarsely ground cacao nibs, 3 g dehydrated raspberries, 3 g dehydrated blueberries (both berries finely ground in a spice mill with a bit of granulated sugar), and 1.5 t. acai powder.