Method

• 1.
  Pick out a bowl to use as the mold for the bombe. It should have a 2-quart capacity (pour 8 cups of water into the bowl to make sure) and ideally be made of metal and have a rounded bottom. Line the bowl with two crisscrossed pieces of aluminum foil, pressing the pieces into the bottom and up the curved sides and smoothing the folds and wrinkles thoroughly. The foil should extend to the rim of the bowl (fold over any excess). Pour 7 cups of water into the lined bowl and mark the water line with a permanent marker or piece of tape. Dump out the water, dry the foil, and transfer the lined bowl to the freezer.
• 2.
  Arrange an oven rack in the center position and preheat the oven to 350°F. Place the almonds on a sheet pan and toast until they’re golden brown and fragrant, 5 to 8 minutes, tossing halfway through. Transfer the almonds to a cutting board and let cool, then coarsely chop and set aside. Turn the oven off.
• 3.
  Place the biscuits in a resealable bag, press out the air, and seal. Set the bag on the work surface and use a rolling pin or the bottom of a heavy saucepan to break the biscuits into small pieces. Continue to crush the biscuits, occasionally shaking the bag so the larger pieces settle to one side, until you have some fine crumbs and some coarse crumbs and a few large pieces. Transfer the crumbs to a separate large bowl.
• 4.
  Remove the chocolate ice cream from the freezer. Take the lid off and slice lengthwise down through the carton with a chef’s knife to cut it in half. Peel away the carton and discard, then cut the ice cream pieces in half again and transfer to the bowl with the crumbs. (If the carton isn’t made of paper, just scoop the ice cream into the bowl.) Working quickly to prevent melting, use a flexible spatula to work the ice cream against the sides of the bowl, mixing in the crumbs, until the ice cream is spreadable and the crumbs are evenly distributed.
• 5.
  Remove the mold from the freezer and scrape in about three-quarters of the chocolate ice cream mixture. Scrape the remaining chocolate ice cream mixture into a smaller bowl, cover, and transfer to the freezer for later. Use the back of a spoon to spread the mixture into the bottom and up the sides of the lined bowl in an even layer, working it up to the line you previously marked all the way around. Return the bowl to the freezer and freeze until solid, at least 1 hour.
• 6.
  Remove the vanilla ice cream from the freezer. Take the lids off and slice open both cartons just as you did for the chocolate, then cut the ice cream into pieces. Transfer the ice cream to a large, clean bowl and work with a flexible spatula until it’s slightly softened and spreadable. Add the cherries and toasted almonds and fold to combine. Remove the mold from the freezer and scrape in the vanilla ice cream mixture. Use the spatula to press it into the cavity inside the chocolate layer, doing your best to eliminate air pockets, and smooth the surface. It should come to just below the top of the chocolate layer. Return the bowl to the freezer and freeze until the vanilla layer is firm, at least 2 hours.
• 7.
  Remove the small bowl filled with the remaining chocolate ice cream mixture from the freezer and stir with a flexible spatula until spreadable. Remove the bombe from the freezer and spread the remaining chocolate mixture evenly over the vanilla layer all the way to the sides. Return the bombe to the freezer and freeze until completely solid, at least 1 hour. Place a serving plate for the bombe in the freezer.
• 8.
  Place the chopped chocolate in a small heatproof bowl. In a small saucepan, heat 1/4 cup (2.1 oz / 60g) of the cream over medium heat just until it’s steaming and bubbling around the sides. Pour the hot cream over the chocolate and let the mixture sit until the chocolate is fully melted, about 3 minutes. Whisk the ganache gently until it’s completely smooth.
• 9.
  Remove the frozen plate and the bombe from the freezer. Place the plate upside down over the bowl, then invert the plate and bowl together. Lift off the bowl and carefully peel away the foil. Pour the ganache over the bombe, pouring onto the highest part of the dome and letting it cascade down the sides in big drips. Before the ganache hardens, shower sprinkles over the top. Return the bombe to the freezer and freeze until the ganache is hardened, about 30 minutes.
• 10.
  In a medium bowl, with a whisk or hand mixer, whip the remaining 1 cup (8.5 oz / 240g) cream on low speed to start and gradually increase the speed to medium-high as it thickens, until you have a softly whipped cream that forms droopy peaks. Remove the bombe from the freezer, slice into wedges with a hot knife, and serve with dollops of whipped cream and hot fudge sauce.
• 11.
  For the hot fudge sauce, in a small, heavy-bottomed saucepan, whisk together the sugar, cocoa powder, and salt to break up any lumps. Add the cream and corn syrup and whisk until the mixture is smooth and well combined, making sure no unincorporated sugar is trapped around the sides. Add the chocolate and bring the mixture to a boil over medium-high, stirring with a heatproof flexible spatula to dissolve the sugar and melt the chocolate. When the mixture comes to a boil, reduce the heat to maintain a brisk simmer and continue to cook, stirring often and making sure to scrape the bottom and sides of the saucepan to prevent scorching, until the mixture is very thick and you see a layer of yellow fat pooling around the sides of the saucepan, 40 to 50 minutes. Remove the saucepan from the heat and pour the mixture into a heatproof medium bowl (scrape down the sides of the saucepan, but not the bottom where some of the mixture may have scorched). Add the butter, vanilla, and 2 tablespoons (1 oz / 28g) water and let sit for 5 minutes, then whisk the mixture, starting from the center of the bowl and slowly working outward, until it comes back together and forms a smooth and glossy sauce. If serving immediately, let the sauce sit at room temperature, whisking occasionally, until it’s warm and the consistency is thick but still pourable, about 5 minutes. If preparing ahead of time, pour the sauce into a 1-pint jar, cover, and chill.