Extra Cheesy Chicken Sliders

Name: Extra-Cheesy Chicken Sliders
Ingredients: 1 (12-ounce) package Hawaiian sweet rolls, such as King’s; 4 ounces sharp cheddar cheese (about 1 cup shredded); 4 ounces low-moisture mozzarella cheese (about 1 cup shredded); 1 clove garlic; 1 pound boneless, skinless cooked chicken; 4 medium scallions; 1/4 cup mayonnaise, preferably Kewpie; 1/4 cup sour cream; 1 tablespoon Dijon mustard; 1/2 teaspoon freshly ground black pepper; 1/4 teaspoon kosher salt; 3 tablespoons unsalted butter; 1 tablespoon white sesame seeds, preferably toasted