01 - Preheat oven to 375°F. Lightly grease a 9x13-inch baking dish with butter or nonstick spray.
02 - Cook lasagna noodles according to package directions until al dente. Drain, rinse briefly with cool water, and lay each noodle flat on a baking sheet or clean towel to prevent sticking.
03 - In a large mixing bowl, combine the shredded chicken, ricotta, mozzarella, Parmesan, minced garlic, parsley, egg, salt, and black pepper. Stir until all ingredients are evenly distributed.
04 - Melt the butter in a medium saucepan over medium heat. Whisk in the flour and cook for 1 minute to form a roux. Gradually pour in the milk while whisking continuously until the mixture thickens, about 3 to 4 minutes. Stir in the Parmesan cheese and garlic powder until smooth. Season with salt and pepper to taste, then remove from heat.
05 - Spread 1/2 cup of marinara sauce evenly across the bottom of the prepared baking dish. Lay a cooked noodle flat and spread 2 to 3 tablespoons of the chicken filling over the surface. Roll the noodle up tightly from one end. Repeat with the remaining noodles and filling, placing each roll seam-side down in the dish.
06 - Pour the creamy Parmesan sauce over the roll ups, followed by the remaining marinara sauce. Sprinkle the mozzarella and Parmesan cheeses evenly over the top.
07 - Bake for 30 to 35 minutes until the cheese is melted, golden, and the sauce is bubbling. Let rest for 5 to 10 minutes before serving.