Preheat oven to 425 degrees F. Line a baking sheet with parchment paper; set aside.

Heat olive oil in a medium skillet over medium high heat. Add onion and cook, stirring occasionally, until golden and caramelized, about 10-15 minutes. Transfer to a plate.

In a large bowl, combine red onion, chicken, cheddar cheese, pineapple, BBQ sauce and cilantro; season with salt and pepper; to taste.

Working one at a time, transfer tortilla to a work surface; place BBQ chicken mixture in the center of each wrapper. Bring the bottom edge of the tortilla tightly over the filling, rolling from bottom to top until the top of the tortilla is reached. Repeat with remaining tortilla and filling.

Place taquitos seam side down onto prepared baking sheet and bake until taquitos are crisp and cheese has melted, about 15 minutes.

Serve immediately with BBQ sauce, if desired.