Place chicken, tomatoes, taco seasoning and onions in the crockpot.
Cook on low for 6 to 8 hours, or high 3 to 4 hours.
Shred the chicken and stir.
Spoon mixture onto flour tortilla.
Top with the Monterey Jack cheese. Fold in half.
Cook on a heated griddle for a few minutes until it begins to brown. Flip.
Continue until all the quesadillas are prepared.
Serve with your favorite toppings and enjoy!
