I've been using the method where you start with a rectangle cut the size of the flying goose (the finished size with the seam allowances) and 2 squares. You mark the squares on the diagonal and sew them onto the top 2 corners of the rectangle, then trim off the fabrics behind. I call it "flippy corners" but I'm sure that's not it's official name.

Ha! That is way too warm. However, I am currently "enjoying" 3 degrees F (-16C) with a wind chill of -12F (-25C). Our summers are lovely so maybe I just need to find a winter retreat some day. : )

I grew up with 100 degree days for weeks at a time. I must say, in all honesty, I prefer the cold.