Preheat oven to 425°F. Then spray a large baking-sheet with olive oil or avocado oil cooking-spray.
In a large bowl, combine oil with onion powder, garlic powder, cumin, chili powder, paprika and sea salt. Add sliced cauliflower and lightly toss to coat.
Put seasoned cauliflower on baking-sheet, spacing out the pieces so they roast instead than steam. Bake for 20minutes, till cauliflower is tender and beginning to brown.
Remove the pan in the oven, push cauliflower together at the middle of the pan. Top cauliflowerwith refried beans, sprinkle with cheese and put in jalapeño pieces on top.
Return to the oven & bake till the beans are warmed through and the cheese has melted for 6-7minutes.
Top cauliflower with chopped red onion, cilantro and tomato. Then add avocado (if desired) and serve straight from the sheet pan or you could even move to a platter for serving.