bomboloni {italian doughnuts}

Name: bomboloni {italian doughnuts}
Prep time: 3 h
Cook time: 10 min
Total time: 3 h 10 min
Cuisine: Italian
Ingredients: 250 g 2 cups bread flour; 250 g 2 cups all-purpose flour; 75 g heaping 1/3 cup granulated white sugar; 100 g 7 tbsp unsalted butter, at room temperature; 20 g fresh cake yeast or 1 package (7g dry instant yeast); 7 g 1 1/2 tsp salt; 150 g 3 whole large eggs; 40 g 2 egg yolks; 110 g 1/2 cup lukewarm water; zest of 1 orange; 1 tsp vanilla extract; granulated sugar (for coating)