Put the cleaned and washed spinach in boiling water and add the butter. Season with salt and boil until the spinach becomes soft. Add the sour cream.
Blend until you get a homogeneous mixture. Make croutons by cutting the bread into small cubes. Brush them with butter and bake them in the oven. They are ready as soon as they become crispy and golden.
Serve the soup in bowls with croutons added in and sprinkle it with fenugreek on top.