Sew the background squares from one corner to the other on two opposing corners of the pink squares. Trim the excess corners off 1/4" beyond the diagonal seam line and then iron the remaining triangles outwards.
Point the pink fabric inwards to create the X's or place the pink fabric crosswise to make the O's.
Because it's so easy, make lots!
I'm going to make three table runners, but laid out altogether, it would make a really nice baby quilt. Hmmmmm...