Step 1

Melt the butter in a stock pot, add the leeks and onions and fry until golden brown (about 10 minutes).

Step 2

Add in the yams then cover with plenty of water and season to taste with salt and freshly-ground black pepper.

Step 3

Bring to a simmer, cover and cook for about 30 minutes, or until the yam pieces are tender.

Step 4

When the soup is almost ready, heat the groundnut oil in a pan.

Step 5

Cut the bread into large cubes and fry in the oil until golden brown all over.

Step 6

Remove the bread with a slotted spoon and set aside on a paper towel to drain.

Step 7

When the yam mixture has cooked, take off the heat and allow to cool slightly then puree in a blender until smooth.

Step 8

Return the puree to a pan and stir in the condensed milk.

Step 9

Allow to heat through then ladle into warmed soup bowls and serve topped with the fried bread croutons.