Pound 4 boneless skinless chicken breasts to approximately ¼ inch thickness.
In a shallow bowl, mix together 1½ cups flour, 1 tsp onion powder, 1 tsp garlic powder, ½ tsp salt, 1 tsp black pepper, and ¼ tsp cayenne pepper.
In a separate bowl, whisk together 2 eggs and 1 cup buttermilk.
Coat each chicken breast in the flour mixture, then dip into the buttermilk mixture, then back into the flour mixture, pressing to coat completely. Place on a plate.
Preheat oven to 200°F.
Heat about 1 inch of vegetable oil in a skillet over medium-high heat to 350°F.
You will have to work in batches for the next step. Gently place each coated chicken breast into the oil and cook for 2-3 minutes per side until the chicken is lightly golden brown. Drain the chicken on a plate lined with a paper towel and then place the chicken on a sheet pan in the oven while you fry the remaining chicken breasts. Allow the chicken to stay in the oven while you prepare the gravy.
For the Gravy:
In a saucepan, melt ½ cup butter over medium heat.
Whisk in ¼ cup flour and cook until combined and lightly browned.
Gradually whisk in 2 cups milk until smooth.
Add ½ tsp salt and ½ tsp black pepper.
Simmer for 3–5 minutes until thickened. Add more milk if too thick or simmer longer if too thin.