Prep the panade: In a large bowl, combine breadcrumbs and milk. Let it sit for 2 to 3 minutes until the crumbs absorb the liquid and look mushy.
Grate and drain veggies: Grate the zucchini and carrot on the fine holes of a box grater. Squeeze the zucchini in a clean towel to remove excess water.
This keeps the meatballs from getting soggy.
Mix the meatball base: To the panade, add ground meat, grated zucchini, carrot, onion, garlic (if using), egg, Parmesan, Italian seasoning, salt, and pepper. Drizzle in the olive oil. Mix gently with a fork or your hands just until combined.
Do not overwork.
Shape: Line a baking sheet with parchment. Scoop 1-tablespoon portions (about 1-inch balls) and roll lightly. Place them close together but not touching.
Bake: Heat oven to 400°F (200°C).
Bake for 10 to 12 minutes, until lightly set and just cooked through. They should still look pale; avoid browning too much.
Optional sauce simmer: Warm marinara in a wide skillet. Add baked meatballs and simmer on low for 5 to 8 minutes.
This keeps them extra juicy and adds flavor without drying them out.
Serve: Let cool slightly. Serve plain as finger food, with a little sauce, or over soft pasta, rice, or mashed potatoes. Cut in half for younger toddlers as needed.