01 - Preheat the oven to 375°F. Lightly grease a 9x13-inch baking dish and set aside.
02 - Bring a large pot of salted water to a boil. Cook lasagna noodles according to package directions until al dente. Drain, rinse gently under cool water, and lay each noodle flat on a clean baking sheet or parchment paper to prevent sticking.
03 - In a large mixing bowl, combine the shredded chicken, ricotta cheese, mozzarella cheese, Parmesan cheese, minced garlic, chopped parsley, egg, salt, and black pepper. Stir until all ingredients are evenly incorporated.
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 constantly. Continue cooking and whisking until the sauce thickens, about 3 to 4 minutes. Stir in the Parmesan cheese and garlic powder. Season with salt and pepper to taste. Remove from heat and set aside.
05 - Pour 1/2 cup of marinara sauce into the bottom of the prepared baking dish and spread it into an even layer.
06 - Lay a cooked lasagna noodle flat on your work surface. Spread 2 to 3 tablespoons of the chicken filling evenly over the noodle, leaving a small border at the edges. Roll the noodle up tightly from one end to the other. Repeat with remaining noodles and filling.
07 - Place each rolled noodle seam-side down in the baking dish, arranging them in a single row. Pour the creamy Parmesan sauce evenly over the roll ups, then drizzle the remaining marinara sauce on top.
08 - Sprinkle the shredded mozzarella and grated Parmesan cheese evenly over the top of the roll ups.
09 - Bake uncovered for 30 to 35 minutes, until the cheese is melted, golden brown, and the sauce is bubbling around the edges. Let rest for 5 to 10 minutes before serving.