1. Prepare the BBQ Chicken Filling:

• Heat the olive oil in a large skillet over medium heat.
• Add the thinly sliced red onion and cook, stirring occasionally, until softened, about 2-3 minutes.
• Add the 3 minced garlic cloves and cook until fragrant, about 30 seconds more, stirring constantly.
• Add the shredded roasted chicken, smoked paprika, Worcestershire sauce, and BBQ sauce to the skillet.
• Stir everything together well to combine. Cook, stirring occasionally, until the mixture is heated through and the sauce has melded with the chicken, about 2-3 minutes. Remove from heat and set aside.

2. Make the Garlic Butter and Prepare Bread:

• In a medium microwave-safe bowl, combine the ¼ cup of butter, 2 minced garlic cloves, and 2 teaspoons of minced fresh parsley.
• Microwave in 20-30 second intervals, stirring in between, until the butter is completely melted and the garlic is fragrant.
• Lay out the 12 slices of bread on your work surface.
• Using a pastry brush, spread the melted garlic butter mixture evenly over one side of each slice of bread.

3. Assemble the Sandwiches:

• Flip 6 of the bread slices over so the unbuttered side is facing up.
• On each of these 6 unbuttered sides, place one slice of Havarti cheese.
• Divide the prepared BBQ chicken mixture evenly among these 6 bread slices, spooning it on top of the cheese.
• Place another slice of Havarti cheese over the top of the BBQ chicken mixture on each sandwich.
• Top each sandwich with one of the remaining 6 slices of bread, ensuring the garlic-buttered side is facing outwards (both the top and bottom exterior of the sandwich should be buttered).

4. Grill the Sandwiches:

• Heat a large non-stick skillet or griddle over medium heat. (You can use the same skillet used for the chicken if wiped clean, or a separate one).
• Carefully place 2-3 assembled sandwiches (or as many as fit comfortably without overcrowding) buttered-side down into the hot skillet.
• Cook until the bottoms of the sandwiches are nicely golden brown and crispy, about 3 to 5 minutes. Press down gently with a spatula occasionally for even browning.
• Carefully flip the sandwiches over using a wide spatula. Reduce the heat slightly to medium-low.
• Continue cooking on the second side until it is also golden brown and crispy, and the cheese inside is fully melted and gooey, about 3 to 5 minutes longer. Adjust heat as needed to prevent burning while ensuring cheese melts.
• Repeat with any remaining sandwiches.

5. Serve:

• Remove the golden, crispy BBQ Chicken Grilled Cheese sandwiches from the skillet.
• Let them rest for a minute or two before slicing (they will be very hot!).
• Slice in half diagonally, if desired, and serve immediately. Enjoy the cheesy, BBQ goodness!