America's Test Kitchen LogoCook's Country LogoCook's Illustrated LogoAmerica's Test Kitchen LogoCook's Country LogoCook's Illustrated Logo

Mirror Cake

By Katie Leaird

Published on January 4, 2023

Time

45 minutes, plus time to make layer cake, plus chilling time

Yield

Serves 16 to 20

WHAT KIDS ARE SAYING

“My favorite part was pouring the glaze on the cake and seeing how majestical it was." —Evelyn, recipe tester, age 9

Mirror Cake

Ingredients

1 (9-inch) frosted layer cake (see note, below)2 tablespoons unflavored gelatin ¼ cup (2 ounces) plus ½ cup (4 ounces) water, measured separately1 cup (7 ounces/198 grams) sugar ½ cup sweetened condensed milk 1 tablespoon vanilla extract 1⅓ cups (8 ounces/227 grams) white chocolate chips ¼ teaspoon black gel food coloring ⅛ teaspoon purple gel food coloring ⅛ teaspoon turquoise gel food coloring

Before You Begin

To get the boldest colors, make sure to use gel food coloring. We love using our Easy Chocolate Layer Cake here, but you can use boxed cake mix and store-bought frosting instead. It’s important to follow the frosting steps in that recipe to create a smooth base for the mirror glaze. You can make a mirror cake with two colors, as in the video, or three colors, as in this recipe.

Instructions

  1. Line rimmed baking sheet with parchment paper and place cooling rack inside baking sheet. Place frosted cake on 9-inch cardboard round and place in freezer while making glaze.
  2. In small bowl, use spoon to stir together gelatin and ¼ cup water. Let sit for 5 minutes.
  3. Meanwhile, in small saucepan, combine sugar, sweetened condensed milk, vanilla, and remaining ½ cup water. Cook sugar mixture over medium heat, stirring occasionally with rubber spatula, until mixture starts to bubble around edges, 5 to 8 minutes. Turn off heat and slide saucepan to cool burner.
  4. Use rubber spatula to scrape gelatin mixture into sugar mixture. Stir until gelatin is dissolved. Add white chocolate chips and stir until melted and mixture is smooth, about 1 minute.
  5. Place fine-mesh strainer in medium bowl. Pour chocolate mixture through strainer (ask an adult for help—saucepan will be heavy); discard solids. Let glaze cool for 15 minutes, stirring occasionally to prevent skin from forming.
  6. Pour ½ cup glaze into liquid measuring cup. Pour another ½ cup glaze into second liquid measuring cup. Add gel food coloring to each glaze and combine in bowl following photos, “Step-by-Step: How to Mix Glaze,” below.
  7. Remove cake from freezer and place on cooling rack set inside parchment-lined baking sheet. Working quickly, pour glaze over top of chilled cake (in center of cake), letting glaze drip down and coat sides of cake (see photo, “Step-by-Step: The Big Pour,” below). Some glaze will drip onto baking sheet—that’s OK!
  8. Let cake sit for 5 minutes, allowing extra glaze to drip off cake. Slide spatula under cardboard round and carefully lift glazed cake. Transfer glazed cake to serving platter and place in refrigerator to chill until glaze is set and no longer sticky, about 20 minutes.
  9. Remove cake from refrigerator and let sit at room temperature for at least 30 minutes or up to 24 hours before serving. To serve, run chef’s knife under hot water, then wipe knife dry with dish towel (ask an adult for help). Slice cake, wetting and drying knife in between slices. Serve.

Mirror Cake

Headshot of Katie Leaird
By Katie Leaird
Save

Time

45 minutes, plus time to make layer cake, plus chilling time

Yield

Serves 16 to 20

WHAT KIDS ARE SAYING

“My favorite part was pouring the glaze on the cake and seeing how majestical it was." —Evelyn, recipe tester, age 9

Ingredients

1 (9-inch) frosted layer cake (see note, below)
2 tablespoons unflavored gelatin
¼ cup (2 ounces) plus ½ cup (4 ounces) water, measured separately
1 cup (7 ounces/198 grams) sugar
½ cup sweetened condensed milk
1 tablespoon vanilla extract
1⅓ cups (8 ounces/227 grams) white chocolate chips
¼ teaspoon black gel food coloring
⅛ teaspoon purple gel food coloring
⅛ teaspoon turquoise gel food coloring

Test Kitchen Techniques

Ingredients

1 (9-inch) frosted layer cake (see note, below)
2 tablespoons unflavored gelatin
¼ cup (2 ounces) plus ½ cup (4 ounces) water, measured separately
1 cup (7 ounces/198 grams) sugar
½ cup sweetened condensed milk
1 tablespoon vanilla extract
1⅓ cups (8 ounces/227 grams) white chocolate chips
¼ teaspoon black gel food coloring
⅛ teaspoon purple gel food coloring
⅛ teaspoon turquoise gel food coloring

Test Kitchen Techniques

Ingredients

1 (9-inch) frosted layer cake (see note, below)
2 tablespoons unflavored gelatin
¼ cup (2 ounces) plus ½ cup (4 ounces) water, measured separately
1 cup (7 ounces/198 grams) sugar
½ cup sweetened condensed milk
1 tablespoon vanilla extract
1⅓ cups (8 ounces/227 grams) white chocolate chips
¼ teaspoon black gel food coloring
⅛ teaspoon purple gel food coloring
⅛ teaspoon turquoise gel food coloring

Test Kitchen Techniques

Why This Recipe Works

The mirror glaze on this show-stopping cake is so shiny, you can see your reflection in it—hence the name! This celebration-worthy dessert is a project, but one that kids (and adults!) will be proud to serve at your next gathering. Ask kids: Have you ever looked into the surface of a calm, smooth lake, pool, or puddle and seen your reflection in the water? The same science lets you see your reflection in the Mirror Cake’s glaze. One reason puddles and mirrors reflect so well is because they’re very smooth. The frosting on a regular cake, no matter how hard you try to smooth it out, is always a little wavy and bumpy. But pouring the glaze on our Mirror Cake forms a very smooth, reflective surface—just like water! (Learn more in “Fun Fact: Putting the “Mirror” in Mirror Cake,” below.) Can kids think of any other foods that they might be able to see their reflection in? (Some examples: a bowl of broth, a smooth bowl of Jell-O)

Want more? Read the whole story

Before You Begin

To get the boldest colors, make sure to use gel food coloring. We love using our Easy Chocolate Layer Cake here, but you can use boxed cake mix and store-bought frosting instead. It’s important to follow the frosting steps in that recipe to create a smooth base for the mirror glaze. You can make a mirror cake with two colors, as in the video, or three colors, as in this recipe.

Instructions

  1. Line rimmed baking sheet with parchment paper and place cooling rack inside baking sheet. Place frosted cake on 9-inch cardboard round and place in freezer while making glaze.
  2. In small bowl, use spoon to stir together gelatin and ¼ cup water. Let sit for 5 minutes.
  3. Meanwhile, in small saucepan, combine sugar, sweetened condensed milk, vanilla, and remaining ½ cup water. Cook sugar mixture over medium heat, stirring occasionally with rubber spatula, until mixture starts to bubble around edges, 5 to 8 minutes. Turn off heat and slide saucepan to cool burner.
  4. Use rubber spatula to scrape gelatin mixture into sugar mixture. Stir until gelatin is dissolved. Add white chocolate chips and stir until melted and mixture is smooth, about 1 minute.
  5. Place fine-mesh strainer in medium bowl. Pour chocolate mixture through strainer (ask an adult for help—saucepan will be heavy); discard solids. Let glaze cool for 15 minutes, stirring occasionally to prevent skin from forming.
  6. Pour ½ cup glaze into liquid measuring cup. Pour another ½ cup glaze into second liquid measuring cup. Add gel food coloring to each glaze and combine in bowl following photos, “Step-by-Step: How to Mix Glaze,” below.
  7. Remove cake from freezer and place on cooling rack set inside parchment-lined baking sheet. Working quickly, pour glaze over top of chilled cake (in center of cake), letting glaze drip down and coat sides of cake (see photo, “Step-by-Step: The Big Pour,” below). Some glaze will drip onto baking sheet—that’s OK!
  8. Let cake sit for 5 minutes, allowing extra glaze to drip off cake. Slide spatula under cardboard round and carefully lift glazed cake. Transfer glazed cake to serving platter and place in refrigerator to chill until glaze is set and no longer sticky, about 20 minutes.
  9. Remove cake from refrigerator and let sit at room temperature for at least 30 minutes or up to 24 hours before serving. To serve, run chef’s knife under hot water, then wipe knife dry with dish towel (ask an adult for help). Slice cake, wetting and drying knife in between slices. Serve.

Gift This Recipe

Enjoyed this dish? Let others know by sharing it as a gift recipe.

This is a members' feature.