PreparationFor cake: Preheat oven to 350°F. Butter and flour three 9-inch-diameter cake pans with 1 1/2-inch-high sides. Sift flour, cocoa powder, baking soda and salt into medium bowl. Mix 2 cups cold water and sugar in large bowl until sugar dissolves. Gradually mix in corn oil and vanilla extract. Whisk in dry ingredients. Divide cake batter among prepared pans. Sprinkle 1/2 cup mint-flavored chocolate chips over cake batter in each pan. Bake cakes until tester inserted into center comes out clean, about 25 minutes. Cool cakes in pans on rack 15 minutes. Cut around pan sides. Turn cakes out onto racks and cool completely. For frosting: Combine powdered sugar, cocoa powder, unsalted butter, 6 tablespoons milk, peppermint extract and vanilla extract in large bowl. Using electric mixer, beat frosting until smooth. Thin with more milk by tablespoonfuls, if necessary. Place 1 cake layer, chocolate-chip side up, on platter. Spread 2/3 cup frosting over. Sprinkle with 1/2 cup chocolate chips. Top with second cake layer, chocolate-chip side up. Spread 2/3 cup frosting over. Sprinkle with 1/2 cup chocolate chips. Top with remaining cake layer, chocolate-chip side down. Spread remaining frosting over sides and top of cake. (Can be made 1 day ahead. Cover with cake dome; let stand at room temperature.) Place striped peppermint candies in heavy plastic bag. Crush with hammer. Sprinkle candies over cake.
PreparationFor cake: Preheat oven to 350°F. Butter and flour three 9-inch-diameter cake pans with 1 1/2-inch-high sides. Sift flour, cocoa powder, baking soda and salt into medium bowl. Mix 2 cups cold water and sugar in large bowl until sugar dissolves. Gradually mix in corn oil and vanilla extract. Whisk in dry ingredients. Divide cake batter among prepared pans. Sprinkle 1/2 cup mint-flavored chocolate chips over cake batter in each pan. Bake cakes until tester inserted into center comes out clean, about 25 minutes. Cool cakes in pans on rack 15 minutes. Cut around pan sides. Turn cakes out onto racks and cool completely. For frosting: Combine powdered sugar, cocoa powder, unsalted butter, 6 tablespoons milk, peppermint extract and vanilla extract in large bowl. Using electric mixer, beat frosting until smooth. Thin with more milk by tablespoonfuls, if necessary. Place 1 cake layer, chocolate-chip side up, on platter. Spread 2/3 cup frosting over. Sprinkle with 1/2 cup chocolate chips. Top with second cake layer, chocolate-chip side up. Spread 2/3 cup frosting over. Sprinkle with 1/2 cup chocolate chips. Top with remaining cake layer, chocolate-chip side down. Spread remaining frosting over sides and top of cake. (Can be made 1 day ahead. Cover with cake dome; let stand at room temperature.) Place striped peppermint candies in heavy plastic bag. Crush with hammer. Sprinkle candies over cake.