In a large skillet melt the butter with the oil over medium-high heat.
Season the chicken lightly with black pepper and garlic powder.
Add to skillet and brown lightly on both sides; remove to a plate.
For the gravy; add in more butter to the skillet only if needed then add in onion and saute for about 3 minutes or until just slightly softened.
Add in garlic and chili flakes; saute stirring for 2 minutes.
Add in all remaining ingredients (start with 1/4 cup milk or even less as the sauce will thin even more as it cooking you can always add in more after) bring to a simmer stirring constantly with a wooden spoon scraping up all the browned bits from the bottom of the skillet; cook until the mixture is combined and bubbly.
Place the chicken back into the pan and turn to coat in the gravy.
Reduce to low heat and simmer uncovered turning the chicken and stirring every so often.
Simmer for about 35-40 minutes or until the chicken is cooked through.