Add the chicken, onion, tomatoes, mushrooms, garlic, broth, and seasonings to the crockpot. Cook on low for 5 to 6 hours or high for 3 to 4 hours. Whisk together the flour and butter. When cooking is complete, remove chicken and shred. Return chicken, along with the flour/butter mixture, coconut milk, and gnocchi. Cook on high for 15 minutes, then add spinach. Cook until spinach has wilted. Serve!