Add cubed butternut squash to a pot of water and bring to a boil. Boil for 10-12 minutes or until squash is fork tender. Drain and mash squash. Set aside.
Season chicken with salt and pepper. Heat 1 tsp olive oil over medium-high heat in a large pan or skillet. Sear chicken on both sides until browned, about 2-3 minutes per side. Set chicken aside.
Add remaining olive oil to the pan or skillet. Add onion and garlic. Sauté until onions are softened and begin to brown on the edges, then add mushrooms and sauté until mushrooms are golden.
Add wine, chicken stock, ground mustard, red pepper flakes and all but 1/4 cup of the coconut milk. Scrape any browned bits of onion and garlic from the bottom of the pan.
Whisk arrowroot flour into coconut milk, then add to the pan and whisk until well incorporated. Bring the sauce to a boil, then lower heat to a simmer and return chicken to the pan. Cover chicken with sauce.
Simmer another 5-10 minutes until the sauce thickens and the chicken is cooked through.
Add broccoli to a microwave safe bowl and cover with a very damp paper towel. Microwave for 3-4 minutes until broccoli is bright green and tender crisp.
Serve chicken and sauce over butternut squash mash with broccoli.
To make this recipe fully paleo compliant, substitute the white wine with chicken stock and a squeeze of fresh lemon juice.