Step 1 Place the sour cream and chipotle in a food processor and puree until smooth.
Step 2 Put the cheese, butter and chipotle mixture in a skillet. Stir over medium heat until the cheese is thoroughly melted.
Step 3Remove the skillet from the heat for 1 to 2 minutes until the cheese mixture firms up slightly. Pour the cheese mixture onto the slices of toast and broil until the tops start to bubble, about 1 minute.