Pound the chicken between two pieces of plastic wrap with the smooth side of a meat mallet to 1/2 -inch thickness, then cut each breast in half to make two portions from each breast half.
Lightly drizzle each portion with olive oil on both sides to prevent the chicken from sticking to the grill pan. Season both sides with salt and pepper.
When the grill (or grill pan) is hot, add the chicken and cook for two minutes, flip over and cook two minutes longer, flip again this time rotating half a turn to achieve perfect grill marks, then once more for the final turn. You are looking to cook the chicken for a total of two-to-three minutes cooking per side (four flips) and an internal temperature of 165°F.
Remove the chicken from the grill to a saucepan then toss in homemade BBQ sauce to infuse the chicken with the flavor of the sauce. Let simmer on low heat until ready to serve.
Meanwhile, spread an even light coating of mayonnaise on the inside top and bottom layer of each bun. Toast the buns on the grill with the remaining grill heat for a minute or two.
For the Sandwich
When the buns are toasted, add the chicken to the bottom bun portion, next add a dollop of creamy coleslaw, a few red onion slices, and two bread and butter pickle slices. Top with the other half of the bun.
 You could also substitute four boneless chicken thighs in place of the chicken breast for this recipe.