01 -
Preheat the oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish.
02 -
Cook the ground beef in a large skillet over medium-high heat for 7-9 minutes, breaking it into crumbles, until cooked through. Season with salt and pepper, then drain well.
03 -
Add the marinara to the skillet and stir until the beef is evenly coated. Simmer for 2 minutes, then remove from the heat.
04 -
Spread the sliced bell peppers across the bottom of the baking dish. Spoon the hot beef and sauce mixture evenly over the peppers.
05 -
Cover the dish tightly with foil and bake for 25 minutes, until the peppers start to soften and the sauce bubbles at the edges.
06 -
Remove the foil, sprinkle the cheese evenly over the top, and bake for 10-15 minutes longer until melted, bubbly, and lightly browned.
07 -
Let the casserole rest for 10 minutes before scooping. Serve as is, or spoon over rice, noodles, or mashed potatoes.