Preheat the oven to 375°F. Place a silicone baking mat on a baking sheet, or line with parchment or aluminum foil. (makes for easy clean up).
In a sauté pan over medium heat, brown the beef and onion together. Discard any excess fat that may have accumulated while browning the beef.
Transfer the beef and onion mixture to a large bowl. Add the cream cheese, pepper jack cheese, Colby jack cheese, diced green chiles, salt, pepper, and cumin to the bowl. Mix to combine.
Add 2-3 T. of meat mixture to each flour tortilla. Roll up and place seam side down on a baking sheet.
Lightly spray the tops of the taquitos with olive oil or avocado oil spray. (Not heavy handed... just a light mist).
Bake for 18-25 minutes or until lightly crisp and golden brown on top. *
Serve with salsa and a garnish of cilantro if desired.