Now that we have our board to guide the shape of our cake you just build the cake up in layers. You do not need to be exact with each addition, as each layer should be bigger (wider) than you need and then you carve the cake to be the exact share you require.
I used a rich chocolate madeira cake with a fudge icing as one I like the taste :-) and two it makes for a strong cake that will keep the shape it is carved into.
As you can see from the picture, once I had the main shape I wanted, I added more fudge icing to form the edges around what would be the opening in the shoe.