In a large bowl, combine flour, remaining 2 tbsp sugar, and salt. Add the yeast mixture, eggs, and vanilla. Mix until a dough forms. Add the softened butter and knead (by hand or mixer with a dough hook) for about 8–10 minutes until smooth and elastic.
3. Let it rise:
Cover the bowl and let the dough rise in a warm spot for 1 to 1.5 hours or until doubled in size.
4. Shape the bomboloni:
Roll out dough on a lightly floured surface to about 1/2-inch thickness. Cut into circles using a 2.5–3 inch cutter. Place on a tray, cover, and let rise again for 30–45 minutes.
5. Fry:
Heat oil in a deep pan to 340–350°F (170–175°C). Fry 2–3 at a time, about 1–2 minutes per side, until golden brown. Drain on paper towels.
6. Coat and fill:
While still warm, roll bomboloni in granulated sugar. Use a piping bag to fill each donut with your choice of filling.
Would you like a recipe for vanilla pastry cream or tips for a Nutella filling?