Dissolve coffee powder in a little boiling water; cool.
Follow the recipe for Beaten Sponge Cake adding dissolved coffee powder to egg yolks and sugar before beating.
Cut cooled cake horizontally into 2 layers and fill with jam.
To make frosting and decoration, blend cornstarch with a little milk in a small bowl.
Heat remaining milk with sugar in a small saucepan.
Stir hot milk mixture into cornstarch mixture.
Return to saucepan and bring to a boil, stirring constantly until thickened.
Dissolve coffee powder in a little boiling water.
Stir into cornstarch mixture.
Return mixture to bowl and cool, stirring frequently.
Cream butter until soft then beat into cooled cornstarch sauce a spoonful at a time.
Mix in powdered sugar.
Spread about half the coffee cream over top and sides of cake.
Mark top of cake into 16 portions with a knife.
Put remaining coffee cream into a pastry bag fitted with a fluted nozzle.
Pipe in a pattern on cake as illustrated.
Decorate with candied coffee beans and almonds.