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.