01 - Preheat the oven to 400°F. Line a baking sheet with parchment paper.
02 - In a large skillet, heat olive oil over medium heat. Add garlic and cook until fragrant, about 1 minute.
03 - Stir in heavy cream and milk. Bring to a gentle simmer, then add Parmesan, salt, pepper, red pepper flakes (if using), and Italian seasoning. Stir until cheese is melted and sauce is smooth.
04 - Add the cooked chicken to the Alfredo sauce. Stir to coat, then remove from heat.
05 - Slice the bread in half lengthwise. In a small bowl, mix softened butter, minced garlic, and parsley. Spread the garlic butter evenly over both bread halves.
06 - Spoon the chicken Alfredo mixture over the bread halves, spreading evenly.
07 - Top with mozzarella and provolone cheese.
08 - Place the bread halves on the prepared baking sheet and bake for 12–15 minutes, or until cheese is melted and bubbly and the edges are golden brown.
09 - Remove from the oven, let cool slightly, and slice into pieces. Serve warm.