1/4 cup softened unsalted butter, divided
2 (10-inch) hoagie buns, sliced lengthwise, but not completely through
2 tablespoons olive oil
1 large yellow onion, diced
1/2 pound ribeye steak, very thinly sliced
Salt, to taste
Freshly ground black pepper, to taste
1 teaspoons granulated garlic, more to taste
4 slices provolone cheese