Bomboloni

For the Doughnuts:

1. Lightly oil a large bowl.
2. In the bowl of a stand mixer, add the flour, ½ cup sugar, and the yeast. Stir to combine. Scatter the softened butter over the flour mixture.
3. In a small bowl, whisk together milk and eggs. Add the milk mixture, vanilla, and salt to the flour mixture.
4. Using the dough hook attachment, beat on low speed until a smooth and elastic dough forms, about 10 minutes. The dough should feel tacky but not stick to a clean finger when quickly touched.
5. Turn the dough out onto a work surface. Knead 4 to 5 times or just enough to shape it into a ball. (You shouldn’t need to flour the surface). Place the dough in the oiled bowl and turn to coat. Cover and let rise in a warm spot until doubled in size, about 1½ hours.
6. While the dough rises, cut 12 (4x4-inch) squares of parchment paper. Place on a baking sheet.
7. Punch down the risen dough and turn it out into a clean work surface. Knead the dough 4 to 5 times and shape it back into a ball. Roll the dough out into a ¾-inch thick rectangle. Using a 3-inch round cookie cutter, cut the dough into 12 rounds. Reroll any dough scraps, if needed. Place each dough round on a parchment square. Loosely cover and let rise in a warm spot until doubled in size, about 1 hour.
8. When the dough is close to done rising, fill a large Dutch oven with oil 3 inches deep. Insert a deep-fry thermometer and place over medium heat until it reaches 300°F to 310°F.
9. Line a rimmed baking sheet with paper towels. Place the remaining ¼ cup sugar in a medium bowl.
10. Working with 2 or 3 at a time, carefully lift each dough round by the parchment and drop dough-side down into the oil. Removing the parchment with tongs. Cook for 2½ minutes then turn over and cook an additional 2½ minutes, or until each side is a deep golden brown. Remove with a slotted spoon or spider and drain on the paper towels. Let cool for 2 minutes.
11. Roll each doughnut in the remaining sugar. Place on a wire rack and cool completely.

For the Filling:

1. Once cool, use the tip of a small knife to make a small incision in the side of each doughnut. Place the desired filling in a piping bag fitted with a large round tip. Insert the tip into each slit and fill. The doughnuts are best when enjoyed the day they are made, however, leftovers can be refrigerated in an airtight container for up to 3 days.