Combine water and oats; cool to room temperature. Cream butter, brown sugar, sugar and vanilla; beat in eggs. Blend in oatmeals mix. Combine flour, baking soda, baking powder, cinnamon and salt. Add to creamed mix. Beat 1 minute on medium speed. Pour batter into a greased and floured 13x9 pan. Chop peanut butter cups and sprinkloe on top of batter (Do Not Stir). Bake at 350 degrees 40-45 minutes.

Frosting: melt butter. Add chocolate and stir constantly over low heat until melted. Pour into a bowl and add remaining ingredients; beat until well blended. Chill to spreading consistency and frost cake.