In a bowl, whisk together the BBQ sauce, apple cider vinegar, brown sugar, and chili flakes. Add olive oil, garlic powder, paprika, cumin, salt, and pepper. Coat the chicken thighs in the marinade, cover, and refrigerate for at least 15 minutes (or up to 2 hours if you’ve got time). This step enhances the depth of flavor, especially important if you’re experimenting with your own grilled chicken sandwich marinade.

Heat a grill or grill pan over medium-high heat. Grill the marinated chicken thighs for about 5–6 minutes per side or until cooked through and nicely charred. Internal temp should hit 165°F. Rest for 5 minutes, then shred or slice thinly. This juicy grilled chicken forms the core of your ultimate bbq chicken sandwich.

Butter one side of each bread slice. On the non-buttered side, layer shredded cheddar cheese, grilled chicken, a drizzle of extra BBQ sauce (go heavy if you like it sticky), jalapeño slices, and more cheddar. Top with the other slice of bread, buttered side facing out.

Heat your skillet over medium-low. Place the sandwich in the pan and cook until golden brown on the bottom, about 3–4 minutes. Flip carefully and cook the other side until the cheese is melted and the bread is deeply golden and crisp—another 3–4 minutes. Press down gently with a spatula for that irresistible melt and crust combo.

Let it cool slightly before slicing in half. The cheese should be gooey, the chicken juicy, and the jalapeños giving it that perfect little snap of spice. This is what we mean when we talk about next-level bbq grilled cheese.