Preheat the oven to 400 degrees F. Spray an 8x8 baking dish with nonstick cooking spray.
Brown the ground beef with the onion and bell pepper. Season with garlic powder, onion powder, salt, and pepper. Cook until the meat is cooked through. Drain any excess grease.
Stir in the Manwich sauce and simmer for 3–5 minutes.
Spread the mixture into the baking dish.
Sprinkle with the reduced-fat cheddar cheese.
Arrange the tater tots in a single layer over the top.
Bake for 30–35 minutes, until the tater tots are crispy and the casserole is bubbling.