Spinach Salad with Grilled Chicken

1-1/4 cups Italian Dressing
1/3 cup finely chopped, drained sun-dried tomatoes packed in oil
4 Tbsp. grated Parmesan cheese
1-1/2 lbs. boneless skinless chicken thighs or breasts
1 cup sliced baby portabello, cremini and/or white mushrooms
1/2 small red onion, thinly sliced
1 pkg. fresh spinach leaves

For marinade, combine dressing, tomatoes and 2 Tbsp. cheese. In large shallow baking dish or plastic bag, pour 1/2 cup marinade over chicken, turn to coat. Cover, or close bag, and marinade in refrigerator, turning occasionally, up to 3 hours. Refrigerate remaining marinade.

Remove chicken from marinade, discarding marinade. Grill or broil chicken, turning once and brushing frequently with 1/4 cup refrigerated marinade, until chicken is cooked thoroughly.

To serve, slice chicken. Arrange chicken, mushrooms and onion over spinach; drizzle with remaining refrigerated marinade. Sprinkle with remaining cheese and, if desired, cracked black pepper.