Preheat & Prepare: Preheat your oven to 375°F (190°C). Generously grease a 12-cup muffin tin with cooking spray or olive oil.
Make the Spaghetti Base: In a large bowl, toss the cooked spaghetti with the beaten egg, Parmesan cheese, 1/2 cup marinara sauce, Italian seasoning, garlic powder, salt, and pepper.
Form the Nests: Divide the spaghetti mixture evenly among the 12 muffin cups. Use your fingers or the back of a spoon to press the noodles against the bottom and sides, creating a well in the center of each cup.
Fill & Top: Spoon about 1 tablespoon of marinara sauce into each nest. Place one cooked meatball in the center of each cup. Top with a generous pinch of shredded mozzarella cheese.
Bake: Bake for 20–25 minutes, until the pasta edges are lightly crisped and golden brown and the cheese is fully melted and bubbly.
Cool & Serve: Let the muffin pan cool for 5–7 minutes. Gently run a knife around the edges to lift them out. Garnish with fresh basil leaves and serve warm with extra marinara sauce on the side.
