Melt the butter in a large skillet over medium high heat, and add the onion and bell pepper. Saute until soft and sweet, and a little golden, about 7 minutes or so.
Add the ground sausage, and cook until browned, breaking it up along the way.
Add the garlic, mustard, & coconut aminos, and stir to combine.
Add the flour and stir to coat the veggies.
Pour in the coconut milk and bone broth, and stir to combine, and then add the pasta. Bring the mixture to a simmer and cook until the pasta is al dente.
Turn the heat off, and stir in the baby spinach to wilt. Season with salt and pepper to your taste. Be mindful that every sausage is seasoned differently, so saltiness will vary.