Place chicken breast strips in a bowl and pour buttermilk over them to marinate for 15 minutes.
In a shallow dish, whisk together 3 tablespoons of flour, garlic powder, onion powder, paprika, sea salt, and black pepper.
Dredge each piece of chicken in the flour mixture, pressing firmly to ensure an even coating.
Heat avocado oil in a large skillet over medium-high heat until shimmering.
Add chicken to the skillet and cook for 5 minutes per side until the crust is golden and the chicken is cooked through.
Remove chicken from the pan and set aside on a plate.
In the same pan, melt the butter and whisk in 1 teaspoon of flour for 1 minute.
Slowly whisk in chicken broth and milk, simmering until the gravy becomes thick and creamy.
Serve the crispy chicken immediately with the warm gravy drizzled over the top.