Place wire racks in 2 foil-lined rimmed baking sheets. Adjust oven racks to lower-middle and upper-middle positions and heat oven to 450 degrees.
Combine bread crumbs and buttermilk in large bowl and let sit, mashing occasionally with fork, until smooth paste forms, about 10 minutes.
Add eggs, beef, pork, prosciutto, Parmesan, parsley, garlic, gelatin mixture, 11/2 teaspoons salt, and 1/2 teaspoon pepper to bread-crumb mixture. Using hands, gently mix until thoroughly combined.
Lightly form about ¼ cup mixture into 2-inch round meatball (about 2 ounces); repeat with remaining mixture to form approximately 40 meatballs. Spray wire racks with nonstick cooking spray and place meatballs, evenly spaced, on racks; roast until browned, about 30 minutes, rotating trays from front to back and top to bottom halfway through.
As the meatballs come out of the oven, I drop them into a pot of my favorite marinara sauce.