Heat a skillet over medium heat. Add ground beef and cook until browned, breaking it into crumbles.

Remove excess grease, then stir in onion, bell pepper, and garlic. Cook until softened, about 3-5 minutes.

Add tomato sauce, ketchup, Worcestershire sauce, mustard, smoked paprika, salt, and pepper. Simmer for 8-10 minutes, stirring occasionally, until the mixture thickens.

Preheat the oven to 350°F. Arrange slider buns on a baking sheet and lightly toast for 3 minutes.

Fill each bun with a generous scoop of the beef mixture and top with cheddar cheese.

Brush bun tops with melted butter, then return sliders to the oven for 5 minutes to melt the cheese.

Garnish with parsley and serve immediately.