Blondie Ice Cream Cake with Fudge Sauce

Rich, buttery blondie serves as the base of this show-stopping cake and is also folded into the vanilla ice cream filling. A birthday is a special day so serve an extra special dessert. A homemade blondie serves as the base for this ice cream cake recipe and more blondie pieces are folded into softened vanilla ice cream. Of course, no ice cream cake is complete without hot fudge sauce and this cake has lots of it.

Blondie Ice Cream Cake:
1 stick + 6 Tbsp. unsalted butter, room temperature
1¾ cups all-purpose flour, unbleached
1 tsp. baking powder
¾ tsp. kosher salt
1 1/3 cups light-brown sugar, packed
1/3 cup granulated sugar
2 large eggs, room temperature
1 1/3 cups semisweet chocolate chips
2 qts vanilla ice cream, softened

Fudge Sauce:
½ cup granulated sugar
3 Tbsp. unsalted butter
¼ tsp. kosher salt
½ cup heavy cream
1½ oz semisweet chocolate, finely chopped (1/3 cup)

Preheat oven to 350°F (180°C/160°C fan, Gas Mark 4). Butter a 9x13" baking pan. Line with parchment, leaving a 2" overhang on long sides; butter parchment.

For the Blondie:
Whisk together flour, baking powder, and salt.

Beat butter with both sugars on medium-high speed until light and fluffy, about 2 minutes. Add eggs, one at a time, beating to combine after each addition. Add flour mixture, stirring just until combined (do not overmix). Fold in chocolate chips to evenly incorporate. Scrape batter into prepared pan; smooth top with an offset spatula.

Bake until a tester inserted in center comes out clean, 35-40 minutes. Let cool completely in pan, then lift out using parchment.

Using the base of an 8" springform pan as a guide, cut half of the cake into a round. Cut remaining half into ¾" cubes. (Reserve scraps for snacking.) Place cake round in bottom of springform pan.

Stir 1½ cups cake cubes into softened ice cream, reserving remaining cubes. Spread ice cream over cake in pan. Wrap in plastic and freeze until very firm, at least 6 hours and up to overnight.

For the Fudge Sauce:
In a small saucepan, stir together sugar and 3 Tbsp. water. Place over low heat until sugar is dissolved. Cover and bring to a steady boil, then uncover and cook, swirling occasionally, until deep amber, 6-8 minutes total. Remove from heat; whisk in butter, salt, and cream (it will bubble up). Add chocolate, stirring until just combined. Transfer to a heatproof bowl and refrigerate, stirring occasionally, until mixture is cool and has consistency of thick hot fudge, 30-45 minutes.

Assembly:
Remove cake from freezer. Use a sharp knife dipped in warm water and wiped dry to loosen cake from sides of pan, then unlatch and remove. Transfer cake to a serving plate. Pour cooled sauce over top, allowing it to drip down sides. Freeze again, at least 1 hour. Garnish with remaining cake cubes. Slice with a sharp knife dipped in warm water and wiped dry before each cut; serve.

Makes 12 servings.

Cook's Notes:
When you make caramel, there are a few secrets to avoiding crystallization. First, heat it initially over a low flame, so that all the sugar crystals fully melt before the mixture boils. Next, once the sugar is all melted, put a lid on the pan until the mixture comes to a steady boil. (The steam created washes down the sides of the pan and prevents new sugar crystals from forming.)