Preheat your oven to 400°F (200°C). If you have a pizza stone or baking sheet, place it inside to heat up.

In a medium bowl, combine the cooked chicken with 1/4 cup of BBQ sauce. Stir until every piece is coated. Set aside.

In a small skillet over medium heat, add 1 tablespoon olive oil. Add the sliced red onion and cook for 5 to 7 minutes, stirring occasionally, until they become soft and slightly golden.

Brush each flatbread with a little olive oil and rub the minced garlic over the surface. Place the flatbreads on the preheated baking sheet or directly on the oven rack if you like them extra crispy. Spread a thin layer of BBQ sauce (about 1 tablespoon per flatbread) on each one.

Evenly distribute the BBQ chicken over the flatbreads. Sprinkle the caramelized onions on top, then add the shredded cheese. If you want a kick, add a few slices of jalapeño or a sprinkle of red pepper flakes.

Bake for 10 to 12 minutes. Keep an eye on them; the cheese should be melted and bubbly, and the edges of the flatbread should be golden brown.

Once out of the oven, let the flatbreads cool for a minute. Then garnish with chopped cilantro and a squeeze of lime if you like. Slice into wedges or squares and serve immediately.