Place butter and shortening in mixer bowl and whip until soft. Continue whipping until mixture is fluffy and creamy. Add Masa Harina gradually, mixing thoroughly. Place corn kernels in blender or food processor and coarsely chop; stir into Masa Harina mixture. Place cornmeal, sugar, whipping cream, baking powder, salt and cold water in a large mixing bowl; mix quickly. Add butter/Masa Harina mixture and mix lightly, just until well blended. Pour into a greased 8-by-8-inch pan. Cover with foil. Place pan in a larger pan and pour boiling water into the larger pan until it reaches halfway up corn-cake pan. Bake in 350-degree oven 40 to 50 minutes, checking water level, adding more boiling water if the level falls below one-quarter of the height of the cake pan. When corn cake is cooked through, remove and allow to stand at room temperature for 15 minutes.