Mince the garlic and the onion. Peel the potatoes and parsnip, and cut them into bite-sized pieces.Heat the olive oil in a large, heavy-bottomed pot, then add the garlic and onion. Cook, stirring, until soft and lightly browned, about eight minutes.
Add the potatoes and parsnip, and cook for about 10 minutes, stirring occasionally, so that the vegetables are golden but not browned.
Add the stock, bay leaves, a bit of salt, and fresh ground pepper. Simmer for 30 minutes or until the vegetables are completely cooked. Using an immersion blender, a food processor, or a regular blender, puree the soup to break down some of the potato pieces (I basically creamed all of it together for no chucks. The finished product reminded me of a rich bisque without the cream of course). Heat the empty pot. Add the spinach and squeeze one half of a lemon, cooking for a few minutes until spinach is all soft and cooked down. Add spinach to pureed soup in batches, blending in between additions so that the soup is smooth and bright green. Taste for salt and lemon and add more of either as you think necessary.