Begin by marinating the chicken. Place the chicken breasts in a large bowl and pour the buttermilk over them. Cover and refrigerate for at least 15 minutes (or up to overnight for more flavor).
In a shallow dish, combine the flour, paprika, garlic powder, onion powder, salt, and black pepper. Mix well.
Remove the chicken from the buttermilk, letting the excess drip off, and dredge each breast in the flour mixture, ensuring every piece is fully coated. Shake off any excess flour.
Heat about 1 inch of vegetable oil in a frying pan over medium-high heat. Once the oil is hot (around 350°F), carefully place the breaded chicken breasts in the pan. Fry for about 5-7 minutes on each side, or until the chicken is golden brown and cooked through (internal temperature should reach 165°F).
Once cooked, transfer the fried chicken to a paper towel-lined baking sheet to drain excess oil.
While the chicken is draining, toast the burger buns in the oven or on a skillet until warm and lightly browned.
Assemble the sandwiches by spreading mayonnaise or your preferred sauce on the bottom bun. Place a piece of crispy chicken on top, followed by a lettuce leaf, tomato slice, and pickles if desired. Top with the other half of the bun.
Serve immediately while hot. Enjoy your crispy chicken sandwich!