Tempered White Chocolate Panels
Cut food-safe acetate into 32 strips, each 2 1/2 inches wide and 24 inches long. Lay them all out on a clean, flat work surface with a little bit of space between them.Advertisement
Chop chocolate with a serrated knife. Place 3 pounds in a dry metal bowl; set remainder aside.
In a saucepan, bring 1 to 2 inches of water to a simmer. Set bowl of chocolate over saucepan. Let chocolate melt, stirring gently with a rubber spatula, until it reaches 115 to 118 degrees on a chocolate thermometer (do not let thermometer touch bottom of bowl, and do not let any water get in the melted chocolate). Turn off heat, and remove bowl from saucepan. Add reserved chocolate pieces; stir until mixture cools to 78 or 79 degrees; remove unmelted pieces. Place bowl back over pan of warm water (do not turn heat back on); stir until thermometer reaches 86 to 88 degrees. Use immediately, before chocolate cools (setting the bowl on a heating pad will keep it from cooling too quickly).
Spread about 1 1/2 ounces of tempered white chocolate over the first acetate strip, spreading chocolate back and forth with an offset spatula until it is smooth and strip is completely covered; some will overlap the edges. Repeat with remaining strips. Let set, about 15 minutes. Then lift each acetate strip (excess chocolate will peel away at edges), and transfer to another flat surface (do not stack).
Using a pizza cutter or sharp knife, cut through the chocolate layer of each strip at 3 1/2-, 4-, 4 1/2-, and 5-inch intervals (cut a roughly equal number of each height). Let chocolate panels set completely, 1 to 4 hours, at room temperature.
Once chocolate is thoroughly set, gently flip over each strip so chocolate is facing down, and peel acetate away from chocolate, leaving a smooth, shiny side to be the outer surface. Use an offset spatula to carefully move panels to a parchment-lined baking sheet (do not stack), and let sit until ready to adhere to cake, up to 3 days.
To apply to buttercream-covered cake, spread a thin layer of buttercream onto one side of each panel below the edge of the cake (for a fondant-covered cake, you can also use a thin coating of melted and cooled white chocolate). Starting at one corner of each tier and moving to the left, adhere panels, overlapping slightly and varying heights (see number of panels in the cook's note). When ready to serve, fill tops of each tier with golden raspberries.
Temperatures vary with different chocolates; call the manufacturer or check the package. Use a highly sensitive chocolate thermometer, and do not use a wood spoon, which may retain odors from other foods.
Number of panels per tier for a square cake: 12-inch tier (4 inches high), 28 panels; 10-inch (4 inches high), 24 panels; 8-inch (3 1/2 inches high), 20 panels; 6-inch (3 inches high), 16 panels.