Dark Chocolate & GInger Muffins

3/4 stick (6 tablespoons) unsalted butter
5 ounces bittersweet chocolate (not extra-bitter), coarsely chopped
1 cup whole milk
2 large eggs
1 1/3 cups all-purpose flour
1/3 cup unsweetened cocoa powder
1/3 cup packed brown sugar
1 1/2 teaspoons baking powder
1/2 teaspoon baking soda
1/2 teaspoon salt
1 tsp ground ginger
3 pieces preserved ginger in syrup, drained and finely chopped plus 2 Tbsp syrup from jar

Place oven rack in middle position and preheat oven to 400°F. Heat butter and half of chocolate in milk in a 2-quart saucepan over low heat, stirring constantly, until just melted. Remove from heat. Cool 15 minutes. Add eggs and whisk until smooth.

Whisk together flour, cocoa, brown sugar, baking powder, baking soda, salt and ground ginger in a medium bowl until combined well. Add chocolate mixture and stir until just combined. Stir in remaining chocolate and preserved ginger with reserved syrup.

Divide among 12 greased (1/2-cup) muffin cups. Bake until a tester comes out clean, 14 to 18 minutes. Cool in pan on a rack 5 to 10 minutes. Yields 12 muffins.