1. Coat a 4-5 quart slow cooker with non-stick spray or use a slow cooker liner 2. Place chicken breasts in the slow cooker 3. Scatter chopped red pepper over the chicken. 4. In a separate bowl, combine Marinara sauce, Alfredo Sauce, 3 tablespoons of the pesto, and the Italian Seasoning. 5. Pour sauce mixture over chicken. 6. Season with salt & pepper. 7. Cover & Crock on LOW for 2 hours. 8. Remove lid and add garlic, chopped mushrooms if using and uncooked pasta into sauce. Stir to combine. 9. Cover & Crock an additional 1.5-2 hours or until noodles are cooked through but not overdone. 10. Remove chicken and cut into 1.5 inch pieces; stir back into pasta. 11. If desired, stir in the remaining pesto for additional flavor after Crocking.