Chocolate Chip Ship Ice Cream Cake

Preheat oven to 350 degrees. Butter a 10-by-5 1/2-inch loaf pan. Dust with cocoa powder; tap out excess. Sift cocoa powder, flour, sugar, baking soda, baking powder, and salt into the bowl of an electric mixer fitted with the paddle attachment.

Add eggs, 3/4 cup warm water, the buttermilk, oil, and vanilla. Mix on low speed until smooth, about 3 minutes. Raise speed to medium; mix 30 seconds.

Transfer batter to prepared pan. Bake until a cake tester inserted into center comes out clean, about 1 hour. Let cool in pan on a wire rack 15 minutes. Run a knife around edges to loosen; invert, and unmold. Let cool completely, right side up. Wrap in plastic. Refrigerate until cold, about 2 hours (or up to 2 days).

Cut chocolate loaf cake into three layers; place one in a loaf pan lined with plastic wrap. Peel paper off container of chocolate-chip ice cream and cut 1-inch-thick slices. Lay slices on cake, cutting to fit; fill in holes with ice-cream pieces. Add another layer of cake and ice cream; cover with remaining cake. Press down lightly and refreeze (at least 3 hours).

Trim cake to create bow and stern. Press on chocolate chips to cover top of ship. Attach mini sandwich cookies to sides of ship. Refreeze (up to 5 hours).

Attach mast (see Cook's Note below) before serving. Pipe whipped cream waves at base of cake just before serving, and sprinkle with blue sanding sugar.