Preheat the oven to 400°F (200°C).

Combine chopped cauliflower, carrots, bell peppers, and red onion on a large baking sheet. Drizzle with olive oil and sprinkle with salt and black pepper. Toss well to coat.

Spread seasoned vegetables in a single layer on the baking sheet and roast for about 25 minutes, stirring halfway through, until golden brown and fork-tender.

In a medium saucepan, heat butter or olive oil over medium heat. Add minced garlic and crushed red pepper flakes, sauté for about 1 minute until fragrant.

Stir in sun-dried tomatoes and soften slightly before adding heavy cream and vegetable broth. Simmer for about 3 minutes.

Incorporate grated Parmesan cheese and balsamic vinegar, stirring until smooth. Keep on low heat until just warm.

Once vegetables are roasted, add them directly to the creamy sauce in the saucepan and stir well to coat. Simmer for an additional 2 minutes.

Remove from heat and stir in freshly chopped basil. Serve warm.