Preheat oven to 350 degrees. Spray a 9x13-baking dish with nonstick cooking spray and set aside.
Using a sharp knife, without separating the rolls, slice them in half. Place the bottom portion inside the prepared baking dish and spread with Dean's French Onion Dip. Top with an even layer of cheese, roast beef, fried onions, and the remaining roll tops.
In a microwave-safe dish, melt garlic butter spread and brush on the top of the rolls.
Bake for 15 minutes, remove from the oven and top with additional Dean's French onion dip. Cut sliders and serve.
In place of garlic butter spread, you can substitute 1/2 cup melted butter mixed together with 1/4 teaspoon garlic powder and 1/2 teaspoon dried parsley.