Preheat oven to 450°F (232°C). Line a large rimmed baking sheet with foil and spray with cooking spray.

Cut tortillas in half.

Heat olive oil in a large cast iron skillet over medium heat.

Add diced onions and minced garlic to the skillet.

Sauté the onions and garlic for 3 minutes until fragrant.

Add diced green chilis, shredded cooked chicken, chicken stock, cumin, and garlic salt to the skillet.

Simmer the mixture for 10 minutes, adding more stock if needed to prevent dryness.

Add baby spinach and cook until wilted.

Remove the skillet from heat.

Spread about 2 tablespoons of the chicken mixture on the center/cut end of a tortilla half.

Top with a handful of shredded pepper jack cheese.

Roll up the taquito tightly from the filling end and place it on the prepared baking sheet, seam side down.

Repeat with the remaining tortillas and filling.

Bake for 7 minutes.

Flip the taquitos over and bake for another 7 minutes until crispy.

Turn on the broiler for the last minute to crisp them up further.

Serve immediately with salsa and guacamole.

Garnish with chopped fresh cilantro.