First, prepare the caramelized onions by peeling and slicing 3 medium yellow onions into strips. Melt 2 tablespoons of butter in a skillet over medium heat, add 1 tablespoon of olive oil and the sliced onions, then cook for 40-45 minutes, stirring occasionally until they turn golden brown. Season with salt and freshly ground pepper to taste, allowing the onions to develop that rich, sweet flavor that pairs so well with the brats.

1-Next, grill the bratwurst: Place the 1 package (19 ounces) of bratwurst on a grill over medium-low heat for 15-20 minutes, turning frequently until browned and the internal temperature reaches 160°F (71°C).

2-For the cheddar cheese sauce, melt 1 1/2 tablespoons of butter in a saucepan over medium heat, then stir in 1 1/2 tablespoons of flour and 1/8 teaspoon of garlic powder. Cook for 1 minute before slowly whisking in 3/4 cup of milk until the mixture boils and thickens.

3-Reduce the heat, stir in 5 ounces of shredded sharp cheddar cheese until fully melted, then add 1 tablespoon of spicy brown mustard and season with salt to taste. If the sauce gets too thick, thin it with a bit more milk.

4-Finally, assemble your dish: Place one grilled brat in each of the 5 brat or hoagie buns, top with the caramelized onions, and drizzle generously with the cheddar cheese sauce.