Stir together softened butter, minced garlic, parsley, Parmesan, garlic powder, oregano, salt, pepper, and red pepper flakes until creamy.
Spread a thin layer of mayonnaise on the outside of each bread slice.
Flip the slices and smear the garlic-butter mixture on the inside faces.
Pile mozzarella and cheddar on two slices. Top with remaining slices, mayo side facing out.
Warm a nonstick skillet over medium-low heat.
Set sandwiches in the skillet and cook until deep golden, 3–4 minutes per side. Cover briefly to melt cheese if needed.
Notes
Switch it up: swap cheddar for provolone, add a tomato slice, or sprinkle extra Parmesan on the outside for a frico-like crust. Serve with warm marinara for dipping, or pair with tomato soup. Leftovers reheat best in a skillet or air fryer to restore crisp edges.This recipe is an original creation inspired by classic Cheesy Garlic Bread Grilled Cheese Recipes flavors. All ingredient ratios and instructions are independently developed.