Mix steel cut oats and water together in pan with lid and let soak overnight. Next morning, cook oats for 15 min. or until oats are softened. Add the butter or margarine to the hot oatmeal. Stir until the butter or margarine melts completely. Add the sugar and beat well. Whisk together the cornstarch, vanilla and water. Beat into the oat mixture. Add cinnamon, buckwheat pancake mix and milk. Blend until it is relatively smooth.
Pour into a well oiled 9 x 13 in. pan. Bake at 350 deg. for about 20-25 minutes or until toothpick comes out clean. Allow cooling.
Consider serving with fruit and a dollop of Cool Whip on top.