In Baking with Less Sugar, Joanne Chang, chef-owner of Boston's Flour Bakery + Café, challenged herself to find ways to sweeten classic treats without using refined sugar. In these minty ice cream sandwiches, the chocolate mousse "ice cream" and cake are both sweetened with bittersweet chocolate, letting the chocolate's richness—brightened by fresh spearmint—be the main flavor.
- 11 oz. bittersweet chocolate, finely chopped (2 3/4 cup chopped)
- 2 cups heavy cream
- 1⁄2 cup packed fresh spearmint or peppermint leaves, roughly chopped
- 1⁄2 tsp. kosher salt
- Unsalted butter, for greasing
- 1⁄4 cup strong brewed coffee, at room temperature
- 5 eggs, separated
- 1⁄4 cup all-purpose flour
Place 3 oz. chocolate (3⁄4 cup chopped) in a bowl and set aside. In a 2-qt. saucepan, bring cream and chopped mint to a simmer over medium heat. Remove from heat and let sit for 30 minutes. Strain cream mixture through a fine-mesh sieve into a bowl and return to the saucepan, discarding the mint leaves. Bring the cream back to a boil and pour hot cream over top of chocolate. Add 1⁄4 tsp. salt and whisk until chocolate is completely melted. Cool, then cover ice cream base; refrigerate overnight.
Heat oven to 350°. Line a baking sheet with greased parchment paper. Pour enough water into a 4-quart saucepan that it reaches a depth of 1". Bring to a boil; reduce heat to low. Place remaining chocolate in a medium bowl; set bowl over saucepan. Cook, stirring, until melted and smooth, about 5 minutes. Remove from heat and whisk the coffee, egg yolks, and the remaining salt into the melted chocolate. Using an electric hand mixer, beat egg whites in a bowl until stiff peaks are held. With a rubber spatula, fold in 1⁄3 of the whipped egg whites into the chocolate mixture. Gently fold in remaining egg whites, followed by the flour. Pour batter onto prepared baking sheet and, using an offset spatula, spread to cover the entire surface. Bake until cake is firm to the touch, 10-12 minutes. Let cake cool in the pan for 30 minutes, then wrap tightly with plastic wrap and freeze for at least 30 minutes and up to overnight.
The next day, remove the cake from the freezer and run a pairing knife along the edges. Invert the cake onto another sheet of parchment and peel off the bottom parchment that is now on top. Cut the cake in half widthwise, cutting through the parchment. Place half the cake on a baking sheet.
Using an electric hand mixer, beat ice cream base in a medium bowl until it stiff peaks form. With an offset spatula, spread into an even layer over the half piece of cake sitting on the baking sheet. Invert the other half of cake on top and press down lightly until flat and even. Freeze entire cake for at least 6 hours, and up to overnight. When ready to serve, remove the top and bottom layers of parchment, and trim into 8"x 12" rectangle. Cut into eight- 3"x 4" sandwiches and serve immediately. Alternatively, wrap well in plastic wrap and store in the freezer for up to three weeks.