Place butter in mixing bowl and whip until soft. Continue whipping until very fluffy and creamy. Add masa harina gradually, mixing, and add water gradually, mixing thoroughly. Place corn in blender or food processor and coarsely chop. Stir into masa mixture.
Place cornmeal, sugar, whipping cream, baking powder, and salt in a large mixing bowl. Mix quickly. Add butter-masa mixture. Mix lightly, until just blended.
Pour into a 8" greased baking pan and cover with foil. Place pan in a larger pan and pour in boiling water halfway up pan containing corn cake.
Bake in a 350° degree preheated oven for 40-50 minutes, checking water level; add more boiling water if necessary.
When corn cake is cooked through, remove from oven and allow to stand at room temperature for 15 minutes before cutting. Cut into squares or use a small ice cream scoop to serve.
