Cook pasta as per package instructions, drain and lay flat on parchment paper.
Preheat large skillet on medium heat and spray with cooking spray. Add garlic and onions, saute until translucent. Add flour and stir it vigorously with onions and garlic. Add milk and stir until combined. Let cook 2 minutes.
Add artichoke hearts, chicken and pepper; stir. Bring to a boil, reduce heat to low-medium and cook for 20 minutes, uncovered. Turn off heat, add spinach and stir to combine.
Preheat oven to 350 degrees. Spray the bottom of 9 x 13 baking dish with cooking spray, add 1 cup of tomato sauce and spread it evenly with spatula.
Fill each pasta sheet with 1/4 – 1/3 cup of chicken artichoke mixture and 2 tbsp cheese. Repeat with remaining pasta and filling. Roll each chicken lasagna roll and place tightly in a baking dish: 6 rolls in 1 row, 2 rows.
Top with remaining 1 cup of tomato sauce and 1 cup of cheese, distributing evenly among all rolls. Bake for 30 minutes. Serve warm.