Prep the oven and pan. Heat the oven to 425°F (220°C). Line a rimmed baking sheet with foil or parchment. Brush or rub the foil with 1 tablespoon of olive oil to prevent sticking.
Make a quick panade. In a large bowl, combine breadcrumbs and milk.
Stir and let it sit 2 minutes until the crumbs absorb the liquid. This keeps the meatballs tender.
Add aromatics and seasonings. Mix in the egg, grated onion, garlic, Parmesan, parsley, Italian seasoning, red pepper flakes (if using), salt, and black pepper.
Fold in the turkey. Add the ground turkey and gently mix with a fork or your hands just until combined. Do not overwork.
The mixture should feel moist and slightly sticky.
Form the meatballs. Lightly oil your hands. Scoop about 2 tablespoons of mixture per meatball (a small cookie scoop helps) and roll into 1 1/2-inch balls. Place on the prepared sheet, spacing them evenly.
Oil and bake. Drizzle or brush the meatballs with the remaining tablespoon of olive oil.
Bake for 14–16 minutes, until just cooked through and the centers reach 165°F (74°C).
Optional broil. For a deeper golden top, switch to broil and cook 1–2 minutes. Watch closely to avoid over-browning.
Serve or simmer. Warm your marinara in a skillet or pot. Add the baked meatballs and simmer 3–5 minutes to let flavors mingle.
Serve over pasta, in a sub roll, or with roasted vegetables.