Served with crusty bread and butter.
Chop the white to light-green part of the leek into moderately sized pieces and discard the dark-green ends.
Melt the butter in a pot on medium-low heat, add chopped leeks and potatoes. Stir until leeks are sweat.
Add stock, bay leaf, pepper and optional ingredients now. Raise heat to medium-high, simmer until potatoes are tender.
About 8 minutes before serving, warm the baguette in a 350°F oven for 5 minutes, then slice it and set out the butter.
After removing the pot from the heat, remove the bay leaf and immersion blend pot until you reach a desired consistency.
Stir in heavy cream and salt to taste.