Use low heat. Melt the butter, then add the flour. Stir until it forms some kind of roux.

Open the can. Add the water to the pan. Stir. Add the rest of the ingredients one by one except the kernels. Stir thoroughly until it forms some kind of thick paste.

Add the kernels. Use medium heat this time. When the soup is bubbling, turn off the stove.

Sprinkle some parsley flakes on the soup. Serve with slices of bread.