Spray a 9”x13” casserole dish with nonstick cooking spray; set pan aside.
Using a large pot, cook frozen tortellini according to package instructions; drain and set cooked tortellini aside.
Place a large, deep skillet over medium-high heat. Once hot, add chopped bacon and cook until crispy. Remove bacon and pat dry with paper towels; set cooked bacon aside.
Drain excess grease from pan, but leave ~2 Tbsp in pan.
Add butter to skillet and place over medium heat. Once butter has melted, add diced bell pepper and onions. Sauté, stirring occasionally, for 4-5 minutes.
Add minced garlic; stir until well combined. Continue sauteing for 1-2 more minutes.
Add flour; stir until well combined. Continue sauteing, stirring often, for 2 minutes.
Slowly pour milk and chicken stock into skillet; stir until well combined. Continue cooking, stirring occasionally, for 7-8 minutes, or until sauce thickens noticeably.
Add salt, Italian seasonings, onion powder, garlic powder, pepper and 1¼ cups grated Parmesan cheese; stir until well combined.
Remove skillet from heat and add broccoli, cauliflower, mozzarella pearls and cooked tortellini (from above); stir until well combined.
Transfer mixture into prepared baking dish.
Cover with foil and bake for 20 minutes.
Uncover dish and sprinkle remaining grated Parmesan and cooked bacon (from above) on top.
Bake uncovered for 5-6 minutes, or until top is golden brown.