For Slow Cooker:
1) Add meatballs, peppers, onions, garlic, and olive oil to a medium slow cooker. Stir together and season with salt and pepper and cook on high for about two hours until peppers are cooked. Keep warm until serving.
1) Add olive oil to a medium skillet over medium-high heat. Add sliced peppers and onions. Cook for 4-5 minutes until veggies start to soften. Then stir in meatballs and garlic and continue to cook for another 3-4 minutes until meatballs are browned in spots and warmed through.
To finish the Sliders:
1) Preheat oven to 350˚ F. Slice slider rolls in half and lay bottom half on a baking sheet. Top each roll with half a slice of Provolone. Place in the oven for 4-5 minutes to lightly toast buns and melt cheese.
2) When buns come out of the oven, top with meatballs, peppers, and onions. Divide them evenly between the sliders and top with top bun.
Serve while warm!