Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.

In a large mixing bowl, combine the ground beef, breadcrumbs, Parmesan cheese, parsley, egg, garlic, onion powder, salt, black pepper, and red pepper flakes. Mix until well combined.

Form the mixture into meatballs, about 1 inch in diameter, and place them on the prepared baking sheet.

Bake the meatballs in the preheated oven for 20-25 minutes, or until they are cooked through and browned on the outside.

While the meatballs are baking, in a small saucepan, combine the sweet chili sauce and sriracha sauce (if using). Heat over medium heat until warmed through.

Once the meatballs are done, remove them from the oven and toss them in the sauce until well coated.

Serve the meatballs warm, garnished with extra parsley if desired.