I finally built up the nerve to try a mirror glaze and I am so glad I did. The recipe for this experiment is from Sugar Geek Show and I definitely recommend it. For the cake, I made a devil’s food box cake replacing the water with milk and oil with butter. After taking the cake out of the oven, I popped it out of the pan and wrapped it several times with plastic wrap before putting it in the freezer for at least an hour. Then, it was time to try for some magic.
1 1/2 cups granulated sugar
2/3 cup sweetened condensed milk
1/2 cup + 1 Tbsp water (first quantity)
8 tsp gelatin powder (4 – 0.25 oz packets)
1/2 cups of water (second quantity)
2 cups (360 g) of high quality white chocolate (I used Ghirardelli white chocolate premium baking bars)
Food coloring (I used Wilton icing colors)
Add the sugar, sweetened condensed milk, and the first quantity of water to a medium sauce pan and heat over medium-low heat, stirring occasionally.
While waiting, pour the second quantity of water into the powdered gelatin and mix with a spoon. Leave to fully absorb for a few minutes.
When the sugar, milk, and water mixture begins to simmer, remove from the heat and add the bloomed gelatin. Stir until the gelatin is dissolved.
Pour the hot liquid on top of the chocolate and leave to sit for 5 mins to melt.
Use whisk to stir the glaze until the chocolate has completely melted.
Separate the glaze into separate containers (keeping the containers the same type will help keep cooling time around the same. Metal bowls will retain heat resulting in a much longer cool down time). Add desired food coloring to each container of glaze and stir until well-mixed.
Leave the glaze to cool. (Now is a good time to take the cake out of the freezer.) Once the glaze cools to 90F*, pour it over the frozen cake which is on top of a cup or cooling rack which is sitting on a tray lined with plastic wrap to catch the drippings. Transfer the cake to the fridge to set for a few hours before serving.
*94F worked fine for me. I got a bit impatient because I made the metal bowl mistake. To remedy the mistake, I transferred the glaze to a plastic bowl.
Stir cooling glaze when ready to pour to ensure good consistency. If one or more containers of glaze get too cool, you can reheat the glaze in a pan or by using a baking torch and stirring.