1 1/2 cups sugar
1 1/3 cups flour
1/2 + 1/16 cups cocoa powder
1 1/8 teaspoon baking powder
1 1/8 teaspoon baking soda
3/4 teaspoon salt
3/4 cup milk
1/2 cup (a little scant) vegetable oil
1/2 Tablespoon vanilla
3/4 cup very hot water
Ice cream, slightly softened
1/2 cup cream
4 oz. semisweet chocolate chips
Heat oven to 350. Grease 13x27 sheet pan and line the bottom and sides with parchment paper.
Sift together the sugar, flour, cocoa, baking powder, baking soda, and salt. Whisk briefly. In separate bowl, whisk together eggs, milk, oil, and vanilla. Add wet to dry ingredients and mix at low speed for 5 minutes. Gradually add the hot water, mixing at low speed just until combined. The batter will be quite thin. Pour into pan. Bake 25-30 minutes.
Let cool in pan. Chill, covered, until ready to build the cake. Cut the cake in two equal halves. Place one piece on a serving platter and spread the ice cream on it all the way to the edges. Place second layer on top. Press down gently. Return to freezer while you make the topping.
In a small saucepan heat the cream to a boil. Pour over chocolate and whisk to make a smooth ganache. Remove the cake from the freezer and quickly spread over the cake.