Raspberry Filled Chocolate Muffins

1 1/2 cups flour
1/4 cup cocoa
1/4 cup granulated sugar
1 teaspoon baking soda
1/4 teaspoon salt
1/2 cup (1 stick) butter or margarine, melted
1 cup milk
1 tablespoon vinegar
1/3 cup raspberry preserves
Confectioners' sugar

Preheat oven to 350 degrees F.
In a large bowl, sift together flour, cocoa, sugar, soda, and salt. Stir and make a well in the center.
Pour the melted butter, milk, and vinegar into the well. Stir until all ingredients are moist.
Place cupcake liners in muffin tin and spoon a full tablespoon of batter into each liner.
Place 1 teaspoon of preserves on top of the batter. Cover with an additional tablespoon of batter, sealing the preserves into the center.
Bake for 20 to 25 minutes. Remove from oven and sprinkle with confectioners' sugar. Let cool on rack.
Yields 12 muffins