Melt butter over med/low heat in med. sized skillet. Add chopped onion to skillet and sauté until tender.
When onions are tender, add crushed garlic and cook for 2-3 minutes.
Stir in flour and cook for another 2-3 minutes.
Add in spices (chili powder, cumin, salt, and oregano) and stir until well combined. I recommend starting with 2 TBSP of chili powder.
Slowly whisk in chicken broth, water, and tomato paste. Raise heat to high and whisk continually until it comes to a low boil.
Taste for seasoning and spice level. Adjust chili powder to taste.
Reduce heat and simmer for 10-15 minutes. Sauce will thicken slightly.