Raspberry Mocha Mousse

12 ounces raspberries
1/2 cup semisweet chocolate chips
3 tablespoons milk
1 1/2 teaspoons vanilla extract
1 teaspoon instant espresso powder
2 eggs, separated
1/8 teaspoon cream of tartar
3 tablespoons granulated sugar
1/2 cup unsweetened whipped cream for garnish

Rinse and drain berries. Set aside while preparing mousse.

Heat the chocolate chips, milk, vanilla extract and espresso powder in a small saucepan over medium-low heat until chocolate melts. Whisk until smooth. Beat in egg yolks, one at a time, and continue to cook and whisk until mixture thickens and reaches 140 degrees F. Remove from heat.

Place egg whites in an oven-proof glass or metal bowl, and set in a saucepan over simmering water. Add cream of tartar and beat until foamy. Gradually add sugar, beating constantly. Beat until whites form soft peaks and sugar is dissolved, about 5 to 7 minutes. Stir 1/4 of the whites into the chocolate mixture and blend. Gently fold in the remaining whites.

Spoon about 1/2 cup of berries into each of 4 stemmed glasses. Divide the mousse among the glasses. Top with remaining berries. Cover with plastic wrap and refrigerate until firm, several hours or overnight.

Serve with a dollop of whipped cream, if desired.