cauliflower soup recipe

2 tablespoons olive oil - 1 large onion, diced - 2 cloves garlic, minced - 1 large head of cauliflower, cut into florets - 4 cups vegetable broth (or chicken broth) - 1 cup heavy cream (or coconut milk for a dairy-free option) - Salt and pepper to taste - Optional: 1/4 teaspoon nutmeg - Fresh parsley or chives for garnish (optional)