Peel and chop the sweet potatoes, then boil them in water for 10 minutes.

While boiling the sweet potatoes, heat a pan with a small amount of butter.

Add sliced onions to the pan and sauté until golden brown.

Drain the boiled sweet potatoes and let them cool slightly.

Add the sautéed onions and boiled sweet potatoes to a blender and blend until smooth.

Transfer the blended mixture to a pot and add the remaining milk. Stir well.

Once the soup starts to simmer, add the cheese slices and stir until melted. Season with salt to taste.

Prepare croutons by frying leftover bread in a pan with butter until golden brown.