1 cup semi-sweet chocolate chips
1/3 cup unsalted butter
3/4 cup buttermilk
1/2 cup sugar
1 egg, slightly beaten
1 1/2 teaspoons vanilla
1 2/3 cup flour
1 teaspoon baking soda
1/2 teaspoon salt
Heaping 1/2 cup milk chocolate chunks
Heaping 1/2 cup white chocolate chunks
Preheat oven to 400 .
Line 12 muffin cups with papers.
In a small saucepan, melt semi-sweet chocolate chips and butter.
Let cool about 10 minutes.
In a small bowl stir together the chocolate-butter mixture, buttermilk, sugar, egg, and vanilla; blend well.
In large bowl, stir to gether flour, baking soda and salt.
Make a well in center of dry ingredients and pour in the chocolate mixture.
Stir until just combined.
Fold in the milk and white chocolate chunks, then spoon into lined muffin cups.
Bake for 20-25 minutes, or until toothpick comes out clean (not counting chocolate chunks!).
Let cool 5 minutes before transferring to a wire rack. Serve warm or cooled.