Ok, doesn't it look so easy when Jenny does it? and no trimming to size either. Mine didn't fit so well -
My 3" squares fell short of a 4" block by 1/2", and after checking out my saved tutes, I found another file for this method, including sizes to cut. It says to cut 3 3/4" squares for 4 1/2" blocks (I did note you needed 4 1/2)