Preheat the oven to 350°F. Spray a 9×13-inch baking dish with nonstick cooking spray.

In a small bowl, mix the melted butter, garlic salt, and Italian seasoning until combined. Set aside.

Carefully split the dinner rolls in half, keeping the tops and bottoms intact as a group. Place the bottom halves of the rolls into the prepared baking dish.

Layer the mozzarella cheese evenly over the bottom halves of the rolls. Add a layer of deli ham, followed by the salami, pepperoni, and an even layer of drained giardiniera. Top with the slices of provolone cheese.

Place the top halves of the rolls back on, aligning them with the bottoms. Brush the tops evenly with the melted butter mixture.

Cover the baking dish tightly with aluminum foil. Bake for 15 minutes, or until the cheese is melted and bubbly.

Remove the foil and bake for an additional 5–10 minutes, or until the tops of the rolls are golden brown.

Remove the dish from the oven, slice the sliders, and serve warm.