Preheat oven to 400F and line a medium sheet pan with parchment paper.
Cut French bread in half lengthwise and then into 1/2-inch slices about 3/4 of the way through loaf. Arrange loaves on prepared sheet pan.
Combine mozzarella and Parmesan in a small bowl. Stuff cheese in between bread slices. Set aside for a moment.
Melt butter in a small saucepan over medium heat. Add garlic and cook 1-2 minutes until fragrant. Remove butter from heat and add Italian seasoning, red pepper flakes if using, and season with salt and pepper to taste. Set butter aside.
Bake bread at 400F 10-15 minutes until bread is golden brown and cheese is melted. Brush warm bread with garlic butter and pull apart for serving warm. Enjoy!
Notes
Storing InstructionsBread is best if served immediately after baking.