I looked up that pattern made with the Marie Antoinette fabric line. What it looks like to me is that you fold the material, match up the seam line, lay the out border to it then sew all three layers. The folded side sticks out giving it the dimension.
I have a sampler hanging on my design wall that I'm doing that very thing with.....just have to hand finish the inner square......one of these days! :lol: