1/2 cup butter, softened
1 cup packed brown sugar
1/2 cup unsweetened cocoa powder
2 Tablespoons milk
2 teaspoons vanilla
1/2 teaspoon baking soda
1-1/3 cups all-purpose flour
1-1/4 cups bittersweet or semisweet chocolate pieces
1 Tablespoon shortening
1/2 cup crushed candy canes (about 6)