How to Make It
Preheat the oven to 325º and grease a 9-by-5-inch loaf pan. In a small bowl, whisk the flour with the baking powder and salt.
In a large bowl, using a handheld electric mixer, beat the two sticks of butter and sugar at medium-high speed until fluffy, about 3 minutes. Reduce the speed to medium-low and beat in the eggs, one at a time, and then the vanilla until combined. Reduce the speed to low and gradually add in the flour mixture until just combined.
Pour the batter into the prepared pan and bake for about 1 hour and 10 minutes, until a toothpick inserted in the center of the cake comes out clean. Let the cake cool completely on a rack, then slice crosswise 1 inch thick.
In a small saucepan, combine the raspberries with the sugar and 1 tablespoon of water and bring to a boil. Reduce the heat to low and simmer for about 8 minutes, until the raspberries are broken down. Transfer the raspberries to a food processor, add the jam and process until smooth; strain through a sieve. Cover and refrigerate until cold.
Line a nonstick 9-inch-by-5-inch loaf pan with 2 overlapping sheets of plastic wrap, allowing a 4-inch overhang on all sides. Arrange a single layer of tightly packed cake slices to cover the bottom, trimming as needed to fill in the gaps. Working quickly, spread 1 pint of the softened ice cream over the pound cake. Cover the ice cream with about 1/2 cup raspberry sauce. Freeze the cake until firm, about 30 minutes. Remove the cake from the freezer and spread the remaining 1 pint of ice cream over the frozen raspberry sauce layer. Top with another single layer of tightly packed pound cake slices (the cake will be slightly higher than the pan). Cover the cake completely with the plastic overhang and freeze until firm, at least 5 hours or overnight.
Just before serving, in a medium saucepan, melt the chocolate with the butter and boiling water over low heat, whisking until smooth. Whisk in the corn syrup and sugar and cook for 6 minutes. Stir in the vanilla and salt.
Loosen the ice cream cake from the pan, open the plastic wrap and invert the cake on a flat serving platter. Remove the plastic wrap. Top the cake with whipped cream, then drizzle with some of the hot fudge, letting it spill down the sides. Top the cake with cherries, then slice and serve.