• Preheat oven to 400°F. Line a large baking sheet with parchment paper.

Bread

• Place the Italian bread cut side up on the baking sheet.
• Spread the softened butter evenly over both halves and sprinkle garlic salt across the surface.
• Bake for 8 to 10 minutes, or until lightly golden and crisp. Remove from the oven and set aside.

Chicken

• While the bread is baking, season the chicken pieces evenly with garlic salt, paprika, kosher salt, and black pepper.
• In a large skillet over medium-high heat, heat the olive oil until shimmering. Add the chicken and cook for 3 to 4 minutes per side, or until golden brown and fully cooked through to an internal temperature of 165°F.
• Transfer the cooked chicken to a plate and tent to keep warm as you continue with the recipe.

Alfredo Sauce

• In a separate saucepan over medium heat, melt the butter. Add the diced onion and cook for 3 to 4 minutes, or until translucent.
• Stir in the garlic and cook for 30 seconds.
• Pour in the heavy cream and bring to a gentle simmer (do not boil). Stir in parmesan, salt, pepper, and crushed red pepper flakes. Continue stirring until the cheese has melted and the sauce has thickened slightly, about 3 to 5 minutes. Remove from heat.

Assembly

• Pour about ¾ cup of Alfredo sauce over each toasted bread half, spreading to the edges. You should have about ½ cup of Alfredo sauce left for serving.
• Top with chicken, distributing evenly over both halves.
• Sprinkle mozzarella and white cheddar cheese over the chicken.
• Return the bread to the oven and bake for 8 to 10 minutes, or until the cheese is melted and bubbly. For a more golden top, broil for 1 to 2 minutes, watching closely to prevent burning.
• Remove from the oven and let rest for 2 to 3 minutes.
• Garnish with parsley, slice, and serve warm with the reserved Alfredo sauce (reheated if needed) for dipping.