01 -
In a large mixing bowl, blend all-purpose flour, granulated sugar, instant yeast, and salt. In a separate bowl, whisk together warm whole milk, eggs, melted butter, and lemon zest if using. Gradually integrate the wet mixture into the dry ingredients, stirring until a soft dough develops.
02 -
Knead the dough on a lightly floured surface for approximately 10 minutes, or until smooth and elastic. Place the dough in a greased bowl, cover with a damp cloth, and set aside in a warm environment to rise for around 1 hour or until doubled in size.
03 -
In a saucepan, gently heat whole milk and granulated sugar over medium heat until just simmering. In a bowl, whisk egg yolks with cornstarch to a smooth consistency. Gradually temper the egg yolk mixture with the hot milk, stirring constantly, and return to the saucepan. Cook, stirring continuously, until the custard thickens. Remove from heat and blend in vanilla extract and unsalted butter. Allow the cream to cool completely.
04 -
Deflate the risen dough and turn onto a floured surface. Roll the dough to approximately 1.25 cm thickness and cut into circles using a 7–8 cm round cutter. Arrange the dough circles onto a parchment-lined baking sheet, cover, and let proof for an additional 30 minutes.
05 -
Heat vegetable oil in a deep fryer or heavy-bottomed pot to 175°C. Fry several dough rounds at a time, turning as needed, until evenly golden brown, about 2–3 minutes per side. Remove using a slotted spoon and drain on paper towels.
06 -
Once the fried doughnuts are cool enough to handle, fill a piping bag with the cooled pastry cream. Puncture each doughnut and pipe in an adequate amount of cream filling.
07 -
Liberally dust filled bomboloni with powdered sugar immediately before serving.