When you are in Rome, don't forget to try maritozzi con la panna! These sweet buns with shipped cream are an authentic treat for the perfect Roman breakfast!
Add the yeast, egg yolks, milk, sugar, vanilla, and salt and stir until you get a sticky smooth dough, about 10 minutes.
Transfer to a lightly floured large plastic container with lid, and let it rise for 4 hours.
Line a large baking sheet with parchment paper.
With lightly oiled hands, form the dough into little ping-pong-sized balls and place on the baking sheet. Cover gently with plastic wrap and let rise in a warm place for an additional 2 hours.
Preheat the oven to 355°F.
When doubled in size, brush the buns very gently with the egg whites, covering the entire surface of the buns.
Bake for 20 to 22 minutes. Remove and let cool on a wire rack.
Measure the cream and powdered sugar into a large bowl and whip with a whisk for about 5 minutes, or until it becomes whipped cream.
Slice each bun across the top, fill with fresh whipped cream, and top with additional powdered sugar and the cocoa powder.