Slice each bell pepper in half. Hollow out each pepper, removing stem, seeds, and membrane. Halved peppers will yield 6 portions. If simply slicing the top off the peppers and stuffing them is preferred, the yield will be 3 larger portions.
If you don't have leftover rice handy (we meal prep ours for the week!), cook rice via your favorie method.
Measure out filling ingredients and pre-heat oven to 350°F.
In a large pan or skillet, brown ground beef and onion until cooked through. Stir in rice, tomato paste, ketchup, mustard, Worcestershire sauce, garlic, salt, and pepper. Mix in cheese. (or save cheese for topping peppers if skipping the cheese sauce)
Place peppers in a lipped baking dish or casserole pan. Pour a cup of water around the peppers (to steam the and soften the peppers while baking) and bake uncovered for 30-35 minutes or until desired tenderness is reached.
While the peppers bake, make the cheese sauce!
Freshly grate your cheddar (pre-shredded cheese won't work here) and measure out all ingredients. This cheese sauce comes together fast!
Warm your milk in the microwave for 30-40 seconds and set aside. Heat a small sauce pot and add your butter. Once melted, add flour and whisk into butter vigorously until they become bubbly and foamy. Continue to cook and whisk constantly for about a minute to cook off the flour taste.
Add warm milk and whisk vigorously into flour mixture. Allow milk to come to a simmer, whisking occasionally as it thickens. Once it has thickened, turn off burner and remove pot from heat. Add cream cheese and whisk until melted. Next slowly add grated cheddar in 3 batches, stirring it in until the cheese is fully melted. I like to keep the pot off the heat here so the cheese doesn't overhead and turn gritty. If you work quickly the milk should be hot enough to melt the cheese. If needed, put back on the still-warm burner to help gently melt the cheese. Season with cayenne pepper and salt and set aside.
Once the peppers are ready, pour cheese sauce over the peppers (add a little, or a lot!) and top with all your favorite burger toppings. Enjoy!