Slice chicken breasts into thin quarter-inch strips and season generously with cumin, chili powder, garlic powder, salt, and pepper. Toss the chicken pieces with the seasonings until every surface is evenly coated with the spice mixture.
Heat olive oil in a large skillet over medium-high heat until shimmering. Cook the chicken for 5–6 minutes per side until golden brown and cooked through to 165°F internal temperature, stirring occasionally for even cooking.
Spread tortilla chips across a large serving platter or baking sheet, creating an even single layer. Distribute the seasoned, cooked chicken pieces evenly across the chips, then combine the cheddar and monterey jack cheeses and sprinkle generously over everything.
Microwave the platter on high for 2–3 minutes until the cheese is melted and bubbly, rotating halfway through cooking time. For stovetop assembly, transfer your cheesy loaded chicken nachos recipe to an oven-safe baking sheet and broil 3–4 inches from the heat for 2 minutes until cheese bubbles.
Top with black beans, corn, diced bell pepper, jalapeños, and cilantro while the cheese is still warm and creamy. Drizzle with salsa and sour cream, then serve immediately with extra salsa and sour cream on the side for individual customization.