Mirror glazes are so fun to pour over frozen mousse cakes because the cake’s surface can be smoothed out first. The unblemished result is so shiny you can see your face in it! This glaze pairs beautifully with this Chocolate Mousse cake.
Chocolate Mirror Glaze
(Make this while your mousse is setting)
4 tsp (12 g) Knox unflavored powdered gelatin (just under two packets)
1/4 cup (60 g) cold water
In a small bowl, dissolve the gelatin in the cold water.
1 cup (206 g) granulated sugar
Scant 2/3 cup (142 g) heavy cream
In a medium pot, bring sugar and heavy cream to a boil over medium heat, stirring until the sugar dissolves and it’s bubbling around all the edges.
2/3 cup (148 g) room temperature water
1/2 cup + 1 tsp (71 g) cocoa powder
In a medium bowl, combine the room temperature water with the cocoa powder, stirring with a spatula until it becomes a uniform paste.
Once the cream mixture has begun to boil, stir the bloomed gelatin into the cream-sugar mixture until dissolved, then stir in the cocoa powder paste until combined.
Remove the pot from the heat and pour the glaze mixture through a mesh strainer over a heatproof bowl to remove any clumps of undissolved cocoa powder.
Use a whisk to remove any lumps, whisking until smooth.
Cover and chill in the fridge (overnight if you want) to set, until ready to use. You can store in the fridge in an airtight container for up to 1 week.
When you’re ready to glaze your cake or entremets, remove the glaze from the fridge and heat in the microwave until it’s between 90°F and 94°F (32 to 35°C), so it’s liquid and pourable and will give your cake a shiny, uniform finish. (It takes about 1 minute 20 seconds in the microwave, stirring every 20 seconds or so).
If it looks like it’s slightly separated, use a hand blender to blitz it together. Make sure to tap the container a bit so that the bubbles from blending go away.
Prepare for the Glaze
After the cake and mousse entremets have completely set, set them a few inches apart on top of a rack over a clean sheet pan. Remove their outer acetate. Make sure the sheet pan has a clean sheet of parchment paper on top because you can reuse extra glaze.
Pour the Glaze
Pour the mirror glaze over the entremets in a smooth, continuous pour until it starts running down the sides. Don’t be too heavy handed with it as it will get a rubbery texture if the glaze is too thick. Have a toothpick ready to pop any bubbles before they set.
Once the glaze has set (10 minutes or so), you can trim the drips away with scissors at the base. Place the cake on a larger cake board or platter.
Do not freeze once the glaze has been put on but do keep it chilled in the fridge for a few hours so that it defrosts (especially applicable if they’ve been frozen) before slicing and serving.
Adapted from a recipe by Dominique Ansel.