Heat the olive oil in a large skillet over medium-high heat.
Add the diced onion and cook for 2-3 minutes until softened.
Add the minced garlic and cook for 30 seconds until fragrant.
Add the ground beef to the skillet. Cook, breaking it apart with a spatula, until browned and cooked through, about 5-7 minutes.
Drain excess fat from the skillet if necessary.
Add the diced red bell pepper, sliced mushrooms, and diced zucchini to the skillet. Cook for 5 minutes until the vegetables begin to soften.
Stir in the cherry tomatoes, dried oregano, dried basil, salt, black pepper, and crushed red pepper flakes.
Cook for an additional 3-4 minutes until the tomatoes soften and flavors combine.
Sprinkle the shredded cheddar cheese evenly over the skillet mixture. Cover the skillet with a lid and cook for 2 minutes until the cheese melts.
Remove from heat and garnish with chopped fresh parsley before serving.