Cut the silk and Mini Waffle fabrics each into 13" strips. Trim off the selvages. They should be exactly the same width but don't worry if they are not the same length, you will take care of that later. (I found it easier to cut the solid Mini Waffle Fabric  with a rotary cutter and tear the slippery silk, which gave it a perfectly straight edge.)

Line up the silk, shiney side down, to one end of the Mini Waffle.

Make sure the sides line up perfectly and pin the two fabrics together along one short side and both of the long sides.

If one of the fabrics in longer than the other simply cut the longer one to meet the shorter one.

Pin all the newly shorn side and you'll be ready to sew.