In a microwave-safe bowl, melt the butter. Stir in minced garlic and parsley (if using).
Dip each frozen dinner roll into the garlic butter, coating completely.
Lightly grease a baking pan or skillet. Arrange the coated rolls in a circular pattern, placing them close together in two rows.
Cover with a clean towel or plastic wrap and let rise in a warm place for 2–3 hours, or until doubled in size.
Preheat oven to 350°F (175°C).
Sprinkle shredded mozzarella evenly over the risen rolls. Add red pepper flakes if desired.
Bake for 18–24 minutes, or until golden brown and cheese is melted and bubbly.
Serve warm with marinara sauce for dipping.