Step 1: Cook the Lasagna Noodles : Bring a large pot of salted water to a boil. Cook lasagna noodles according to package directions until al dente. Drain and lay noodles flat on a baking sheet lined with parchment paper to prevent sticking.
Step 2: Prepare the Filling : In a large mixing bowl, combine shredded chicken, ricotta cheese, mozzarella, Parmesan, spinach, egg, garlic powder, Italian seasoning, salt, and pepper. Stir until everything is well mixed and creamy. Taste and adjust seasoning if necessary.
Step 3: Make the Sauce (if using white sauce) : In a saucepan, melt butter over medium heat. Add flour and whisk constantly for about 1 minute to form a roux. Slowly pour in milk, whisking until smooth and thickened (3–5 minutes). Stir in Parmesan cheese, minced garlic, salt, and pepper. Remove from heat and set aside.
Step 4: Assemble the Roll-Ups : Preheat oven to 375°F (190°C). Spread a thin layer of sauce (white or marinara) on the bottom of a baking dish. Lay one lasagna noodle flat on a clean surface. Spread 2–3 tablespoons of filling evenly over it. Roll the noodle up gently and place seam-side down in the baking dish. Repeat with remaining noodles and filling.
Step 5: Top and Bake : Pour remaining sauce evenly over the roll-ups. Sprinkle extra mozzarella and Parmesan on top. Cover with foil and bake for 25 minutes. Remove foil and bake uncovered for another 10 minutes until bubbly and golden. Let rest for 5 minutes before serving.