Adjust oven rack to middle position and heat oven to 450 degrees.
Spray 8-inch square baking pan with vegetable oil spray.
Combine 1 pound ground beef, ½ cup panko bread crumbs, ½ cup whole-milk ricotta, 1 egg, 1 teaspoon Italian seasoning, 1 teaspoon table salt, ½ teaspoon granulated garlic, and ¼ teaspoon pepper flakes in large bowl.
Mix with your hands until thoroughly combined.
Form mixture into about twenty 1½-inch meatballs and transfer to prepared pan (meatballs will be touching).
Roast until meatballs are browned and register 165 degrees, about 20 minutes.
Pour 3 cups marinara sauce over meatballs, then continue to roast until sauce is bubbling all over, about 10 minutes.
Bring 4 quarts water to boil in large pot.
Add 1 pound spaghetti and 1 tablespoon salt and cook, stirring often, until al dente.
Drain pasta and divide among individual bowls.
Top each bowl with sauce and meatballs, dollop with extra ricotta, and serve.
