French Dip Bake | Lazy Cooking

Ingredients

• 2 tablespoons olive oil
• 2 large onions, thinly sliced
• kosher salt, to taste
• 2 tablespoons unsalted butter, melted, divided
• 4 cups beef broth
• 1 (2-ounce) package onion soup and dip mix
• 2 1/2 pounds deli roast beef, thinly sliced and cut into 1-inch-long strips
• 1 (12-count) package slider potato rolls
• 1 (16-ounce) block Swiss cheese, sliced