Martha Stewart Almond-Crunch Ice Cream Cake

Directions

• Toast the almonds: Preheat the oven to 300 degrees with the rack in the center, then spread 2/3 cup blanched whole almonds on a rimmed baking sheet. Bake 12 to 15 minutes until golden, then let them cool completely on a wire rack.
• Grind the almonds: Pulse the cooled almonds with 2/3 cup cake flour in a food processor for about 30 seconds. You want a fine, even grind, so stop before it turns into paste.
• Prepare the pans: Butter two 7-inch round cake pans with 1 tablespoon unsalted butter. Line them with parchment and butter the parchment too, so the delicate cakes release cleanly.
• Whip the egg whites: Beat 6 egg whites and a pinch of salt on medium speed until soft peaks form. Raise the speed to high and add 1/2 cup sugar gradually, beating about 4 minutes until stiff and glossy, then move the whites to another bowl.
• Beat the egg yolks: Clean the mixer bowl, then beat the 6 egg yolks with 2 teaspoons vanilla extract. With the mixer on high, add the remaining 1/2 cup sugar gradually and beat about 5 minutes until pale and thick.
• Fold the batter: Fold the egg-white mixture into the yolk mixture, then fold in the almond mixture in three additions. Divide the batter between the pans and smooth the tops with an offset spatula.
• Bake the cakes: Bake 18 to 20 minutes, until a tester inserted in the centers comes out clean. Cool the pans completely on a wire rack, then turn out the cakes and wrap them in plastic until you need them.
• Make the almond crunch: Raise the oven to 325 degrees. Toss 1 cup sliced almonds with 6 tablespoons sugar and 2 tablespoons water, then spread them on a parchment-lined baking sheet. Bake about 25 minutes until golden, then cool completely.
• Make the syrup: Bring 1/2 cup sugar and 1/3 cup water to a boil in a small saucepan over medium heat, stirring occasionally. Once the sugar dissolves, take it off the heat and stir in 2 tablespoons amaretto, if using, and 1/2 teaspoon almond extract, then let it cool.
• Split the cakes: Use a serrated knife to split each cake horizontally into two equal layers. That gives you four thin layers to stack with the ice cream.
• Line the springform pan: Cut three 24-by-6-inch parchment strips and stack them, then line the sides of a 7-inch springform pan with them. Brush the tops of the cake layers generously with syrup and set one layer in the pan.
• Layer with ice cream: Beat 4 pints softened vanilla ice cream in a chilled mixer bowl on medium-low for about 2 minutes until spreadable. Spread about 2 cups over the first layer, crumble 1/2 cup almond crunch on top, add a second cake layer, and freeze about 20 minutes until firm.
• Repeat and freeze: Repeat with 2 cups ice cream and 1/2 cup almond crunch between each layer, then finish with a cake layer. Freeze 1 hour.
• Frost and serve: Just before serving, whisk 3/4 cup cold heavy cream and 2 tablespoons confectioners' sugar to medium peaks in a chilled bowl. Release the springform sides and set the cake on a platter, then tuck parchment strips under the edge. Frost the top and sides, remove the strips, and garnish with the remaining almond crunch.