Prep your space: Preheat the oven to 400°F (200°C). Line a sheet pan with parchment for easy cleanup. Warm the marinara in a saucepan over low heat.

Mix the meatballs: In a large bowl, combine ground meat, egg, almond flour, parmesan, parsley, garlic, onion powder, oregano, red pepper flakes, salt, and black pepper. Mix gently with your hands until just combined. Don’t overmix or the meatballs can turn dense.

Shape: Roll into 16 even meatballs, about 1 1/2 inches each. Lightly oil your hands if the mixture sticks.

Brown or bake: For best flavor, heat 1 tablespoon olive oil in a large skillet over medium-high heat. Sear meatballs in batches until browned on two sides, 3–4 minutes total. Transfer to the sheet pan. Alternatively, brush with olive oil and bake directly.

Bake to finish: Bake the meatballs on the sheet pan for 10–12 minutes, or until the centers reach 160°F (71°C) for beef. They should be juicy but fully cooked.

Sauce the meatballs: Add the baked meatballs to the warm marinara. Simmer on low for 5 minutes so they soak up flavor. Taste and adjust salt in the sauce if needed.

Prep the rolls: Split your gluten-free rolls and arrange on a clean sheet pan. Brush the cut sides lightly with olive oil. Toast in the oven for 3–4 minutes until the edges are just crisp.

Assemble: Spoon a little marinara onto each roll. Nestle 3–4 meatballs into each, then top with more sauce. Sprinkle generously with mozzarella (and extra parmesan if you like).

Melt the cheese: Return the subs to the oven for 3–5 minutes, just until the cheese is melted and bubbly. For a golden top, switch to broil for 1–2 minutes, watching closely.

Finish and serve: Garnish with chopped basil or parsley. Serve hot with extra napkins and the remaining sauce on the side.