Mix 1/2c chopped pecans,flour,cayenne and pepper. Dredge chicken breasts in mixture. Heat 2 T butter and 1/8c oil in deep,wide skillet. On med-high heat,brown breasts on both sides.,in batches. Add 2T butter and 1/8c oil for second batch Remove to paper towel and then keep warm in oven.
Reduce heat to med,add remaining pecans,onion and tomatoes and stir till heated through. Stir in 1 to 2 Tbs dredging mix. Slowly pour in milk to make gravy of desired consistency. Add dash of tabasco to taste. Return chicken breasts to pan,spoon sauce over and serve.