Preheat the oven to 400 degrees F. Cut the slider buns in half, lengthwise, and place onto a parchment paper lined baking sheet. Toast in the oven to 5-8 minutes.

While the buns are toasting, add a large skillet onto the stove over medium heat. Let it warm for 3-4 minutes, then add a drizzle of olive oil and butter. Once the butter is melted, add diced onions and sugar. Cook for 5 minutes, until softened and slightly golden brown.

Then add ground beef, onion powder, garlic powder, kosher salt, and black pepper. Break up the ground beef and cook until the meat is no longer pink, about 7-10 minutes. (if there's a lot of excess fat, drain it off to prevent the bread from becoming soggy)

Add mustard and ketchup to the ground beef, toss until mixed in, then add 4 slices of American Cheese. Remove from heat and continue to stirring until the cheese is melted.

In a small bowl, mix together mayo and mustard and use a brush or back of a spoon to lather across the buns.

In a separate bowl, mix together the garlic butter mixture. Combine melted butter, minced garlic cloves, and fresh parsley.

Add the ground beef mixture to the bottom half of the buns and place 4 slices of American cheese on the top half of the buns. Place the top half onto the bottom half, then brush the garlic butter mixture on top of the rolls. Bake for 10-15 minutes, until the cheese is melted.