Heat 1 tsp olive oil over medium-high heat in a large skillet. Add kale and toss with Dijon mustard until kale is bright green and has softened to desired texture.
Heat remaining 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, chicken tenders, and sautéed kale evenly among 4 serving containers.