Preheat oven to 400 degrees F.

Toss the cauliflower with half the oil and season with salt and pepper.

Lay on a baking sheet and roast for 15-20 minutes, until browned and tender.

Remove from oven and toss with the butter and blend with an immersion blender or mash.

Season the chicken breast with salt and pepper. Heat the remaining oil in a hot skillet (preferably cast iron) over medium high heat.

When oil shimmers, place chicken skin side down and cook 5-6 minutes, then flip to cook through, until internal temperature reaches 165 F. 

Set chicken aside and add a tablespoon of water and the spinach. Season with salt and stir just until wilted. 

Place cauliflower mash on a plate, top with spinach and then chicken. Serve with pan sauce.