Cream the sugar and eggs. Beat in the oil. Stir together the flour and baking powder. Add the flour mixture alternately with the milk to the batter.
Pour half of the batter into a greased jelly roll pan.
Mix the cocoa powder and the 1 tablespoon of milk into the second half of the cake batter. Pour the chocolate half of the batter very carefully over the white batter already in the pan.
Sprinkle the cherries over the chocolate batter.
Bake for 25-30 minutes in a 350 degree oven.
Let the cake cool completely. When it is cool, spread the cream mixture over the cake.