Hot Fudge Pudding Cake

Hot Fudge Pudding Cake 1 cup sugar 1/2 cup Dutch-processed cocoa powder 1 cup all-purpose flour 2 teaspoons baking powder 1/4 teaspoon salt 1/2 cup milk 4 tablespoons (1/2 stick) unsalted butter, melted 1 large egg yolk 2 teaspoons vanilla extract 1/2 cup semisweet chocolate chips 1 cup boiling water Vanilla ice cream or whipped cream Adjust oven rack to middle position and heat oven to 350 degrees. Spray 8-inch square glass or metal cake pan with cooking spray. Whisk 1/2 cup sugar with 1/4 cup cocoa in small bowl. Whisk flour, remaining 1/2 cup sugar, remaining 1/4 cup cocoa, baking powder, and salt in a large bowl. Whisk milk, butter, egg yolk, and vanilla in medium bowl until smooth. Stir milk mixture into flour mixture until just combined. Fold in chocolate chips. Using rubber spatula, scrape batter into prepared pan and spread into corners. Sprinkle reserved cocoa mixture evenly over top. Gently pour boiling water over cocoa. Do not stir. Bake until top of cake looks cracked, sauce is bubbling, and toothpick inserted into cakey areas comes out with moist crumbs attached, about 25 minutes. Cool on rack for at least 10 minutes. To serve, scoop warm cake into individual serving bowls and top with vanilla ice cream or whipped cream