Combine coffee and marshmallows in top of a double boiler. Cook over boiling water, stirring constantly, until marshmallows melt. Remove from heat; cool to room temperature. Chill to consistency of unbeaten egg whites. Add vanilla, and stir well.
Fold whipped cream into coffee mixture. Spoon into a lightly oiled 4-cup mold. Chill overnight. Unmold onto a serving plate, and garnish with almonds. Spoon onto individual serving plates.