Add butternut squash to a large pot. Cover with water and bring to a boil for 10-15 minutes or until squash is tender. Drain water and add remaining squash mash ingredients. Mash until it reaches desired consistency, then stir in chopped spinach.
Heat 1 tsp olive oil over medium-high heat in a large skillet. Season chicken on both sides with Montreal Steak Seasoning and add to skillet. Cover and cook on each side about 3-4 minutes or until cooked through.
Divide butternut squash mash and chicken tenders evenly among 4 serving containers.