Preheat the oven to 375 degrees Fahrenheit to bake the chicken evenly.
Mix chicken breast with BBQ sauce, chicken broth, garlic powder, smoked paprika, onion powder, sea salt, and black pepper in a bowl until well coated.
Transfer the mixture to a baking dish and cover with aluminum foil to keep it juicy.
Bake for 25 to 30 minutes until the chicken is cooked through and tender enough for shredding.
Use two forks to shred the cooked chicken.
Heat corn tortillas in a dry skillet sprayed with avocado oil until crisp.
Spread refried beans on each tortilla, add shredded chicken, sprinkle mozzarella cheese, diced red onion, fresh cilantro, and drizzle extra BBQ sauce on top.
Serve the tostadas immediately.
Notes
Consider adding pre-shredded rotisserie chicken for time-saving, or switching mozzarella for pepper jack cheese for extra spice.