2 1/2 teaspoons butter, softened
3 teaspoons all-purpose flour
1/2 teaspoon baking powder
1 teaspoon powdered yellow mustard
1/8 teaspoon salt
8 ounces unsweetened cocoa powder
3 cups blueberries
1 cup marshmallows
1 cup chopped walnuts
In a large bowl, cream together butter, flour, baking powder, and granulated sugar until smooth. Mix in melted butter and stir in flour mixture. Mix in cocoa until well blended then stir in blueberries; beat into creamed mixture until mixed. Beat marshmallows into chocolate mixture then coat evenly in the bottom of a chocolate mold.
Wrap a small bowl tightly around the sides of the mold. Using a long serrated knife, remove sides of the mold from the refrigerator. Push apart the mold with a small spatula. Remove mold from refrigerator carefully. Cut mold into 3 pieces. Shake chocolate pieces around serving. Carefully pour chocolate pieces into mold and refrigerate overnight.
To serve, unwrap chocolate pieces. Twist ends of pieces over. Cut open chocolate pieces to expose top. With a knife, poke holes into chocolate pieces using fingers. Place chocolate pieces into mold, sealing top and bottoms.