Traditional petits fours are made of white cake (such as Lady Cake), split and filled with jam and iced with white, pink, and green fondant. You can create interesting and equally elegant petits fours from any cake, filling, and frosting you choose.
The Cake: Hot-Milk Sponge Sheet, or any cake or sponge sheet normally baked in a jelly roll is a very good choice. However, you can bake any cake batter in a 17 1/2 x 11 1/2-inch jelly-roll pan lined with wax or parchment paper. Baking time will be 10 to 15 minutes, at the temperature recommended for the cake. Watch carefully and bake just until the top of the cake springs back when lightly pressed and a toothpick inserted into a few places comes out clean. Let cool completely in the pan on a rack before filling and frosting.
Filling the Cake: If the finished cake is 1/2 inch tall or less, cut it in thirds crosswise and spread two of the pieces with jam (heated and strained or pureed for easy spreading) or a filling or buttercream of your choice. Stack the layers with the uncoated piece on top. If the finished cake is 1 inch or more tall after baking, cut it into thirds to make it easier to handle, then cut each piece into two or three layers with a serrated knife before filling. (If the cake is rich, donΓÇÖt bother splitting or filling itΓÇösimply cut and glaze it.) Place the filled cake strips on a cookie sheet and cover the top and sides with plastic wrap. Place a second cookie sheet on top and weight with canned goods to level and compact the layers so they will not come apart when cut into small shapes. Refrigerate for several hours, until firm, or wrap and freeze for up to 3 months.
Cutting and Glazing the Petits Fours: If desired, first brush hot strained preserves over the filled cake strips and top with a 1/8-inch-thick layer of rolled marzipan. With cookie or canapé cutters, cut the cake into small squares or diamonds, rounds or hearts, or other shapes. If you have not covered the cake with preserves and marzipan, you can brush the top and sides of each cut shape with hot preserves now, or spread a thin coat of buttercream on the tops and sides. Refrigerate to set the coating before glazing. Place the cakes slightly apart on a wire grid or a rack set on a baking sheet. Spoon Bittersweet Chocolate Glaze, Chocolate Ganache Glaze, or Fondant Icing, over each one (see Glazing Petits Fours). Once the glaze or fondant is set, you can decorate the petits fours with pieces of candied violets or rose petals, candied fruits, dragées, sliced almonds or pistachios. Or pipe dainty designs with melted chocolate or tinted fondant. If you like, serve in pleated paper cups. Petits fours can be completed up to 24 hours in advance.
