Patty Melt on Pumpernickel

Melt the 2 tablespoons butter over medium heat in a large skillet. Cook onion, stirring occasionally, for 20 minutes or until tender and golden brown.
Combine ground beef, steak sauce, garlic powder, oregano, and pepper in a large bowl. Shape into four 4-inch patties that are 1/2 inch thick.
Heat the skillet over medium-high heat. Cook patties for 8 to 10 minutes or until cooked through and no longer pink, turning once. Drain fat from skillet and wash skillet.
Place 4 slices of bread on a cutting board. Top each with 1 slice of cheese, a beef patty, 1/4 of the onions, 1 slice of cheese, and another slice of bread. Brush outside of sandwiches with 2 tablespoons melted butter. Preheat the clean skillet over medium heat. Cook sandwiches, half at a time, for 6 minutes or until cheese melts and bread is toasted, turning once.
[Cleaning tip: Once the stove top is cool, wipe up any oil splatters or spills with Clorox® Disinfecting Wipes*.]