Sweet-Potato-Cake Ice Cream Sandwich with Caramel Sauce and Praline

Preparation

1. For Cake

   Step 1

   Preheat oven to 350°. Butter a 9x5x3" loaf pan. Pierce sweet potato all over with a fork. Heat in microwave on high until sweet potato is tender when pierced with a skewer, turning once, about 10 minutes. Cool sweet potato slightly. Peel sweet potato. Transfer to a bowl; mash with fork.

   Step 2

   Whisk all-purpose flour and next 6 ingredients in a medium bowl. Using an electric mixer, beat sugar and butter in a large bowl until well blended. Beat in vanilla and ½ cup sweet potato puree (reserve remaining puree for another use). Beat in sour cream, then eggs, blending just until combined. Add dry ingredients and beat on low speed just until blended, then beat on high speed, about 30 seconds.

   Step 3

   Transfer batter to prepared pan. Bake until a tester inserted comes out clean, about 1 hour. Cool cake in pan on a wire rack, at least 10 minutes. Turn out onto rack; cool completely.

2. For Caramel Sauce

   Step 4

   Stir sugar and ⅓ cup water in a heavy large saucepan over low heat until sugar dissolves. Increase heat to high and boil without stirring until syrup is a deep amber color, occasionally brushing down sides of pan with a wet pastry brush and swirling pan, about 7 minutes.

   Step 5

   Remove from heat. Add cream (mixture will bubble vigorously). Stir over low heat until smooth. Stir in lemon juice. Remove from heat and set aside.

3. For Praline

   Step 6

   Spray a rimmed baking sheet with nonstick spray. Stir sugar and 2 Tbsp. water in a heavy small saucepan over low heat until sugar dissolves. Increase heat to high and boil without stirring until syrup is a deep amber color, occasionally brushing down sides of pan with a wet pastry brush and swirling pan, about 6 minutes. Add nuts (do not stir). Quickly pour mixture onto prepared baking sheet. Cool completely. Break praline into pieces. Transfer to a food processor and blend until finely ground.

   Step 7

   Cut cake crosswise into twelve ¾"-thick slices (discard end pieces). Place 6 slices on work surface. Top each with 1 cup ice cream. Top with remaining cake slices; press slightly to adhere. Freeze sandwiches until firm, about 1 hour.

   Step 8

   Stir reserved caramel sauce over medium heat until heated through. Cut each sandwich diagonally in half. Place 1 slice on each of 12 plates. Spoon warm caramel sauce over; sprinkle with praline and serve.