Melt the butter, oil and cocoa power in the microwave or on the stove top. Stir in sugar, eggs, vanilla, and salt. Add the boiling water at the end. Pour into a 9 inch square pan. Bake at 350 for 20 minutes. Take pan out of the oven. Spread or spoon dulce de leche on top. Sprinkle on Flaked salt. Bake an additional 10 minutes. Cool on wire rack.