In a large pot heat the oil over medium heat. Add the yellow onion and green onions and cook until begin to soften – about 5 min. Stir in the garlic, then add potato and spinach. Pour over the broth and bring to a boil. Cook, stirring occasionally until the spinach become bright green and potatoes are tender – about 15 min. Season with salt and pepper. Blend the soup until it gets smooth, then stir in the cream.
For the croutons melt the butter and toss the bread cubes. Mix them well so all pieces are coated. Spread them evenly on a baking sheet lined with parchment paper. Bake at 375° F/ 190° C for about 12 to 18 min, making sure to stir them regularly.
