Place 8 tostada shells on a baking sheet and bake for 3–5 minutes until warmed through.
While the tostadas are warming, heat 1 can refried pinto beans and 2 cups shredded cooked chicken in the microwave or on the stovetop until heated through.
In a large mixing bowl, combine 2 cups shredded cooked chicken, 1 cup salsa, and 2 tablespoons taco seasoning. Stir until evenly coated.
Divide the chicken mixture evenly among the tostada shells.
Top with 1 cup shredded cheddar cheese and 1 cup shredded Monterey Jack cheese.
Add 1 shredded head romaine lettuce, 1 diced tomato, ½ diced red onion, 1 diced avocado, and chopped fresh cilantro.
Add a dollop of sour cream to each tostada, if desired.
Serve immediately while warm and enjoy.
Notes
You can bake regular corn tortillas until crispy to make your own tostadas if you can't find any at your store.For the shredded chicken, you can use any leftover chicken you have in the refrigerator, store bought shredded rotisserie chicken or make your own shredded chicken in a crock pot. Crock Pot Instructions: If you do not have cooked shredded chicken, you can easily make the chicken in the crock pot. Place raw breasts chicken, salsa and taco seasoning in a crock pot. Cook on low for 6-8 hours (or on high for 3-4 hours) until the chicken is easily shreddable. Shred the chicken and then assemble the tostadas based on the instructions.