Preheat oven to 350°F. Line a 9x13 baking sheet with parchment paper.
In a pan, cook onions with oil, 1 tablespoon butter, salt, and black pepper until soft and slightly caramelized. Set aside.
1 tablespoon olive oil, 1 tablespoon unsalted butter, ⅛ teaspoon coarse kosher salt, ⅛ teaspoon black pepper, 2 cups yellow onions
Place bottom rolls on baking sheet. Layer 6 cheese slices, roast beef, caramelized onions, then another 6 cheese slices.
12 slices provolone cheese, 1 pound deli roast beef
Add top rolls.
12 Hawaiian rolls
Mix 3 tablespoon melted butter, maple syrup, Worcestershire sauce, mustard, and garlic powder. Brush mixture on top.
3 tablespoons unsalted butter, 2 tablespoons maple syrup, 3 teaspoons Worcestershire sauce, 2 teaspoons spicy brown mustard, ¼ teaspoon garlic powder
Cover with foil and bake 15-20 minutes until heated through and cheese melts. Top with poppy seeds before serving. Garnish with parsley before serving.
1 teaspoon poppy seeds, 1 tablespoon parsley