Preheat oven to 350 degrees. Place florets, garlic and oil in a resealable bag. Toss to coat. Lay in a single layer on a baking sheet, sprinkle with salt and pepper and roast for approximately 15 minutes or until desired tenderness.
Place basil, garlic, walnuts, salt and pepper in a food processor. Pulse to combine. Add cheese and pulse to combine. Slowly drizzle oil into running processor, about 1 tablespoon at a time until desired consistency is reached.
Add pesto to cauliflower as desired either toss and heat or use as a sauce/topping.