INGREDIENTS :
Bread: 3 cups (all-purpose flour is also fine)
Fast-acting dry yeast: 2 to 1/4 teaspoons
Salt: 2 teaspoons
Granulated sugar: 1/4 cup + more for coating
Lemon: 1 (zested)
Egg: 2 (lightly beaten)
Whole milk: 3/4 cup
Softened butter: 1/2 stick (about 4 tablespoons)
Vanilla extract: 1 teaspoon
Vegetable oil, for frying
Chocolate-hazelnut spread, jam or pastry cream, for filling
DIRECTIONS :
Step 1:
In the beginning, pick a large bowl or the bowl of a stand mixer fitted with a dough hook and combine together the flour, yeast, salt, sugar, and lemon zest. You’ll need to add the eggs, milk, butter, and vanilla extract, mixing well. You can then knead the dough in the stand mixer or if making the dough by hand around 2 minutes and then tip it onto a floured work surface and knead for 5 minutes, or until it’s smooth and elastic but still quite sticky. Finally, be sure to transfer the dough to a large, lightly oiled bowl. Always remember to cover with plastic wrap. And please let rise in a warm place until doubled in size, about 1 hour.
Step 2:
Okay now, roll out the dough with a rolling pin until about 3/4 inch thick. Then, using a round pastry cutter, cut the dough into disks the size of a cup. Immediately place the dough on a baking sheet lined with parchment paper, covering with plastic wrap, and let rise for another 1 hour.
Step 3:
Heat oil to 350 F in a large, deep pan. After that, you may want to fry the doughnuts in batches, turning halfway through the cooking time, until golden brown, about 4 to 5 minutes. When finished, remove using a slotted spoon and then drain on paper towels. At this point, dredge the doughnuts in granulated sugar until completely covered.
Step 4:
Spoon your favorite filling into a piping bag fitted with a medium nozzle. To finish, make a small hole in the side of each doughnut, push in the nozzle and squeeze to fill the bomboloni, and Serve warm.