Essential green soup

Heat a glug of olive oil in a large pot over medium heat. Add 1 large peeled and diced onion and 2 peeled and minced garlic cloves, and sauté gently until the onion is soft and translucent, 10 minutes. Add 750ml (3 cups) vegetable stock to the pot and bring to a simmer. Add 500g broccoli florets and simmer, 15 minutes, before adding 350g chopped baby marrow. Simmer for a further 10 minutes and add 200g baby spinach leaves, and continue simmering, 5 minutes. Remove from heat and blend until smooth. If necessary, add a little more stock to thin the soup down, then season to taste with salt, freshly ground black pepper and chopped chives.