Preheat oven to 425°F. Spread out 36 pepperoni slices on a wire rack on a foil-lined baking sheet. Bake 4 to 5 minutes or until pepperoni is crispy. Set aside.
Preheat grill to medium-high heat. Sprinkle both sides of slider Burgers with steak seasoning and garlic salt.
Grill, covered, 3 to 5 minutes per side or until no longer pink. Add cheese. Grill 1 minute longer to melt cheese.
Serve sliders on buns with marinara sauce and 3 pepperoni slices on each.
