Preheat and prep: Set your oven to 425°F (220°C). Place a large oven-safe skillet (cast iron works great) on the stove.

Mix the meatballs: In a large bowl, combine ground meat, egg, almond flour, Parmesan, minced onion, minced garlic, parsley, salt, pepper, and a pinch of red pepper flakes if using. Mix gently with your hands until just combined. Don’t overmix or the meatballs can turn dense.

Shape: Roll into 16–18 meatballs, about golf-ball size. Lightly oil your hands to prevent sticking.

Brown the meatballs: Heat oil in your skillet over medium-high. Add meatballs in a single layer without crowding. Sear 2–3 minutes per side until browned. Work in batches if needed. They don’t need to be cooked through yet.

Add marinara: Lower heat to medium. Return all meatballs to the skillet and pour in the marinara, spooning sauce over the tops. Simmer 5 minutes to start melding flavors.

Cheese it up: Sprinkle mozzarella evenly over the meatballs and sauce. Add extra Parmesan for a saltier, nuttier finish.

Bake: Transfer the skillet to the oven. Bake 10–12 minutes, until the meatballs reach an internal temperature of 165°F (74°C) and the cheese is melted and bubbly.

Optional broil: For golden, blistered cheese, switch to broil for 1–2 minutes. Watch closely.

Rest and garnish: Let the skillet rest 5 minutes. Scatter torn basil on top and finish with a light drizzle of olive oil if you like.

Serve: Spoon into bowls or over zucchini noodles, spaghetti squash, or sautéed greens. Finish with cracked black pepper and more Parmesan.