Roasted cauliflower with rocket walnut pesto sauce

Ingredients

• 2 large cauliflower heads, cut in half
• 2 tbsp olive oil
• a pinch of salt
• a pinch of pepper
• pesto sauce with rocket and walnuts (for serving)
• ¼ cup of walnuts, finely chopped
• ¼ cup of hazelnuts, finely chopped
• ¼ cup of parsley leaves, finely chopped
• ¼ cup of raisins
• 1 tsp lemon peel, grated
• ¼ tsp ground red pepper
• 2 tsp extra virgin olive oil