Warm the chicken. In a skillet over medium heat, toss the shredded rotisserie chicken with cumin, chili powder, garlic powder, salt, and pepper. Heat for 3–4 minutes until warmed through and fragrant. Set aside.
Heat the beans. In a small saucepan or microwave-safe bowl, warm the refried beans until spreadable and hot, about 2 minutes.
Prep your tostada shells. If using store-bought shells, you can crisp them in the oven at 350°F for 3–4 minutes for extra crunch. If frying your own, heat 1/2 inch of oil in a skillet and fry corn tortillas for 1–2 minutes per side until golden and crisp. Drain on paper towels.
Layer it up. Spread a generous layer of warm refried beans on each tostada shell. Top with the seasoned chicken, then sprinkle on the shredded cheese.
Add the toppings. Pile on the shredded lettuce, pico de gallo, avocado, jalapeños, and a dollop of sour cream.
Finish and serve. Garnish with fresh cilantro and a squeeze of lime juice. Serve immediately while the shells are still crispy.