In the bowl of a stand mixer fitted with the dough hook attachment, beat flour, milk, sugar, melted butter, eggs, yeast, garlic powder, and salt at low speed for 3 minutes. Increase mixer speed to medium, and beat for 1 minute. Spray a large bowl with cooking spray. Place dough in bowl, turning to grease top. Cover with plastic wrap, and refrigerate overnight.

Remove dough from refrigerator, and let come to room temperature, 1 to 1½ hours.

In a medium stockpot, pour oil to a depth of 4 inches, and heat over medium heat until a deep-fry thermometer registers 325°F (170°C). Place a wire rack over a paper towel-lined baking sheet.

Divide dough into 12 (106-gram) pieces. Working with one piece of dough at a time, use your hands to press dough into a 4-inch round. Place 2 to 3 tomatoes and 2 mozzarella pearls from Roasted Tomato and Marinated Mozzarella Filling in center of round. Bring edges of dough around filling, and pinch to seal. Roll dough gently on a lightly floured surface to help seal dough and shape it into a round. Repeat with remaining dough and filling.

Preheat oven to 350°F (180°C). Place Parmesan in an even layer in a shallow bowl.

Working in batches, fry doughnuts until deeply golden brown and reaches the internal temperature of 190°F/88°C to 200°F/93°C, 5 to 6 minutes. Remove using a slotted spoon, and place on prepared rack. Let drain for 30 seconds; toss in Parmesan to coat. Place on a baking sheet.

Bake for 8 to 10 minutes. (This ensures that doughnuts are cooked all the way through without overbrowning in the fryer.) Let cool for at least 5 minutes before serving.