Add the oil to a large pan, add the onions, and cook for 2-3 minutes while stirring until slightly soft. Add the chicken, garlic powder, paprika, Worcestershire sauce, and BBQ sauce. Mix together until everything is coated. Turn off the heat and set aside.

In a microwaveable bowl, add the butter, garlic powder, and dried parsley and microwave for 10-30 seconds, or just until melted. Place the 8 pieces of bread on parchment paper and spread the butter mixture on only one side of all the pieces of bread with a baster.

Flip each piece of bread over, butter side down, and add a slice of cheese to 4 of the slices. Then, add the chicken mixture on top of each cheese slice, dividing it evenly. Place 4 more cheese slices on top of each one. Next, place the other pieces of bread on top of the cheese; make sure the buttered sides are facing out, not in.

Spray a large pan with nonstick cooking oil and cook the grilled cheese over medium to low heat for about 3-4 minutes on each side, or until you get the color you want on the bread. Slice, serve, and enjoy!