Heat a large skillet over medium heat and add the olive oil.

Add in the onions and sauté for 2–3 minutes, stirring occasionally, until they’re just beginning to soften.

Add the chicken, garlic powder, paprika, Worcestershire sauce, and BBQ sauce. Stir it all together until the chicken is fully coated. Turn off the heat and set the pan aside.

In a small microwave-safe bowl, combine the butter, garlic powder, and dried parsley. Microwave for 10–30 seconds, just until the butter is melted stir to combine.

Lay out 8 slices of bread on a sheet of parchment paper. Using a pastry brush, baster or spoon spread the butter mixture on one side only of each slice.

Flip the slices over so the buttered sides are facing down. Place a slice of cheese on four of the slices. Spoon the chicken mixture evenly over the cheese. Top with another slice of cheese, then place the remaining slices of bread on top—buttered side up this time.

Spray a large skillet with nonstick cooking spray and heat it over medium-low.

Grill the sandwiches for 3–4 minutes on each side, or until the bread is golden and crispy and the cheese is melted. Slice, serve warm, and enjoy!