Garlic Parmesan Style Baked Mashed Potatoes

INGREDIENTS

• 8 medium Russet potatoes, peeled and cubed
• 4 tablespoons unsalted butter
• 1 teaspoon kosher salt
• 1/2 teaspoon garlic salt
• 1/2 teaspoon freshly ground black pepper
• 1 cup warmed milk
• 1/4 cup grated Parmesan Cheese
• 1 1/2 cups pasta or marinara sauce
• 1 1/2 cups shredded mozzarella cheese