Place 1 pound 9oz brownie mix and 1 pound 9oz cake mix and the 10oz water to the bowl of a stand mixer fitted with the paddle attachment. Mix for one minute on low speed, scrape down the bowl. Add 12oz water and 3oz oil and mix 1 minute on low speed, scrape the bowl again, then mix for 2 minutes on second speed. Spray desired size bundt pans with pan spray, deposit batter, and bake at 350F until cake springs back lightly when touched. Let cake cool 5 minutes, depan and let cool completely. Ice cake and serve.