如何用图形路径完全替换WPF按钮的内容？

I've deconstructed a standard WPF button using Blend and have managed to create a nicely styled button, but I cannot figure out how to make the path fill the interior of the button space (the button width and height). I am also not sure if I need to specify ContentPresenter or even if it is correct. I am after the text in the middle of the button (as normal) but with my graphic path behind it.I've deconstructed a standard WPF button using