I haven't done this, but have read instructions. Unfortunately, I can't remember where they are or I'd send you a link. The easiest way is to add a sashing around each block, whatever width you want. Mark a point on the outside edge of the sashing on each side of the block, the same length from the right or left hand corner (depending on which way you want the block to lean). Then cut from point to point around the square. You need to make sure that there's at least a 1/4" space between the corner of the apple block and the cut edge of the sashing so you don't cut off any of the block when you're sewing them together. The wider you cut the sashing, the more the tilt of the inside blocks.
I hope this makes sense to you.