1. PRE-HEAT the oven to 425F and bring a large pot of water to a boil.
2. TOSS the cauliflower in 2 tablespoons of olive oil, season with salt and pepper.
3. PLACE on a sheet tray and roast in the oven until golden brown.
4. Meanwhile, in a large skillet SAUTE the onion in 2 tablespoons of olive oil.
5. COOK the pasta according to package directions.
6. RESERVE 1 cup of the cooking liquid and add it to the onions.
7. ADD the pasta to the sauce and cook for 1 minute over medium heat, stirring frequently until it becomes creamy.
8. ADD the cauliflower, capers and raisins and toss to combine.