In a large skillet, heat 2 tablespoons of olive oil over medium heat. Add 1 chopped yellow onion and sauté for about 4–5 minutes until it becomes soft and translucent. Stir in 3 crushed garlic cloves, 1 teaspoon of dried thyme, and a pinch of chilli flakes, cooking for another 1–2 minutes until the garlic is fragrant but not browned.

Add 4 cups of chopped cauliflower to the skillet, stirring to combine with the aromatic mixture. Pour in 1 cup of vegetable stock or water, season with salt and pepper, cover, and let it simmer for 10–12 minutes.

Remove the skillet from heat and carefully blend the cauliflower mixture until smooth using an immersion blender or transfer it to a countertop blender. Stir in 1 cup of heavy cream and let the sauce simmer on low heat for an additional 5 minutes.

While the sauce simmers, melt 2 tablespoons of butter in a separate frying pan over medium heat. Add 1 cup of fresh ciabatta breadcrumbs and 2 crushed garlic cloves, tossing frequently until they turn golden brown and crispy.

Bring a large pot of salted water to a rolling boil and add 12 ounces of rigatoni pasta. Cook according to package instructions until al dente, typically 10–12 minutes.

Pour the creamy cauliflower sauce over the drained rigatoni, tossing everything gently to combine. If the sauce seems too thick, gradually add the reserved pasta water until the desired creamy consistency is reached.

Serve the creamy cauliflower rigatoni pasta immediately in warm bowls, topped with the crispy garlic breadcrumbs, grated Parmesan cheese, and freshly chopped parsley.