2-2/3 cups chopped dark chocolate or chocolate chips
1/2 cup heavy or whipping cream
2 tablespoons light corn syrup
1 teaspoon vanilla
1 teaspoon espresso powder
13 marshmallows, halved around the circumference
1/2 cup chopped walnuts
Line an 8" x 8" square or 9" round pan with parchment, and grease the parchment. If you don't have parchment, use waxed paper or plastic wrap.
Combine the chocolate, cream, espresso powder, corn syrup, and vanilla in a microwave-safe bowl. Heat the mixture in the microwave till the cream is hot and the chocolate has softened. Stir till the chocolate has melted and everything is smooth.
Spread about 3/4 cup of the melted chocolate in the bottom of the pan.
Space the marshmallow halves atop the chocolate. Distribute the walnuts evenly in the spaces between the marshmallows.
Spread the remaining chocolate atop the marshmallows and walnuts, spreading to the edge of the pan so that everything is covered.
Refrigerate for an hour or so, to set the chocolate. Remove from the refrigerator, and loosen the candy from the edges of the pan.
Bring to room temperature, and leave in the pan, covered with plastic, till you're ready to cut into squares
Makes 12-16 pieces