Preheat the oven to 400°F. Line a rimmed baking sheet with parchment paper.
Arrange the cauliflower florets in a single layer across the baking sheet. Drizzle the melted butter over top, sprinkle with salt, and toss to coat.
Roast the cauliflower on the top rack for 15 minutes.
While the cauliflower is roasting, heat a large sauce pan over medium. To the pan, add the tomatoes, sun-dried tomatoes, garlic, bell pepper, chorizo, basil, and black pepper. Once the sauce is hot and starts to bubble slightly, reduce the heat to medium-low and simmer for 10 minutes. Transfer the sauce to a high powered blender or a food processor and pulse until smooth. Alternately, you can skip this step and leave it chunky.
Pour the sauce over top of the cauliflower and roast for an additional 10 minutes.
Remove the tray from the oven, sprinkle the cheese over top, and bake for an additional 10 minutes or until the cheese is melted.