You can keep the spirit of this 4-ingredient bake and still make small changes. If green bell peppers are too strong for someone at your table, use a mix of green and red or yellow peppers for a milder, sweeter flavor. Any thick tomato-based pasta sauce works; choose a plain marinara, a garlic and herb version, or even a mushroom variety for more depth.
For the cheese, mild cheddar, Colby Jack, or Monterey Jack all melt nicely; if you like a little more punch, use sharp cheddar, but it will taste a bit stronger and saltier. To stretch the dish for a crowd, serve it over cooked egg noodles or rice instead of increasing ingredients—this keeps the recipe true to its easy 4-ingredient nature.
If you’d like a little heat, use a spicy pasta sauce or sprinkle a pinch of red pepper flakes over the top before baking (this would be an optional extra, not one of the main four ingredients). For food safety, always cook the ground beef until it is no longer pink and reaches an internal temperature of 160°F (71°C); drain off excess grease so the casserole doesn’t become oily.
When baking, be careful removing the foil so you don’t get burned by steam, and let the dish rest briefly before serving so the hot cheese doesn’t cause burns. Leftovers should be cooled, covered, and refrigerated within 2 hours, then reheated until steaming hot before eating.