In a mixing bowl, combine the warmed whole milk with the active dry yeast. Allow this mixture to sit undisturbed for around 5 minutes, until it becomes frothy and bubbly, indicating the yeast is active.
In a separate bowl, whisk together the all-purpose flour, granulated sugar, and salt until well combined.
To the yeast mixture, add the room temperature eggs and the melted butter. Stir until everything is thoroughly mixed. Gradually add the flour mixture to the wet ingredients, stirring until a soft dough begins to form.
Transfer the dough onto a lightly floured surface and knead for approximately 8-10 minutes, until the dough is smooth and elastic to the touch.
Place the kneaded dough into a greased bowl, cover it with a clean kitchen towel, and allow it to rise in a warm environment until it doubles in size, about 1 to 1.5 hours.
While the dough rises, chill a mixing bowl in the refrigerator. Once chilled, add the heavy cream and vanilla extract, then beat on medium-high speed until soft peaks form. Set aside in the refrigerator to keep cool.
After the dough has risen, punch it down to release the air. Roll it out on a lightly floured surface to about 1/2 inch thickness. Use a round cutter (approximately 3 inches in diameter) to cut out circles.
Transfer the cut dough circles to a parchment-lined baking sheet, cover them with a towel, and allow them to rise again for about 30 minutes, until puffy.
In a deep pot, heat vegetable oil to 350°F (175°C). Carefully place the doughnuts into the hot oil in batches, frying them for about 2-3 minutes on each side or until they are golden brown. Use a slotted spoon to remove them and let them drain on paper towels.
Once the bomboloni have cooled slightly, use a piping bag fitted with a filling tip or a skewer to fill each doughnut with the whipped cream mixture.
Generously dust the filled bomboloni with powdered sugar just before serving.
Notes
Arrange the bomboloni artfully on a decorative platter, sprinkle with additional powdered sugar, and consider serving alongside a bowl of fresh fruit for a vibrant touch of color.