Heat the oven: Preheat to 425°F (220°C).
Lightly oil a 9x13-inch baking dish or sheet pan.
Season the cauliflower: Toss florets with olive oil, chili powder, smoked paprika, cumin, garlic powder, onion powder, salt, and pepper. Spread in an even layer on the pan.
Roast: Bake for 20–25 minutes, flipping once halfway through, until the edges are browned and the centers are tender but not mushy.
Cook the protein: While the cauliflower roasts, warm a skillet over medium heat. Add the onion and a small drizzle of oil.
Cook 3–4 minutes until softened. Add the ground beef or turkey (or plant-based crumbles) and the minced jalapeño if using. Cook, breaking it up, until browned and cooked through.
Season lightly with salt and a pinch of chili powder.
Add beans and corn: Stir in the black beans and corn. Cook 1–2 minutes to warm through. Remove from heat.
Layer the bake: When the cauliflower is done, gather it to the center of the pan.
Spoon the salsa or enchilada sauce over the cauliflower. Scatter the meat-and-bean mixture evenly on top. Sprinkle with pickled jalapeños if you like heat.
Top generously with shredded cheese.
Bake to melt: Return to the oven for 5–7 minutes, until the cheese is fully melted and bubbling around the edges.
Add fresh toppings: Remove from the oven and top immediately with scallions, tomatoes, cilantro, and diced avocado.
Finish and serve: Add dollops of sour cream or Greek yogurt. Squeeze fresh lime over the top. Serve straight from the pan with extra salsa on the side.