When I was living in Hawaii I would see these flannel type blankets that were great for newborns to toddlers. Although there are variations this one is like what I remember seeing there. It is two layers of flannel sew together usually at least 20 inches square. This one pictured above is 24 X 39 inches. You use it to swaddle a baby or a baby blanket. It is just the right thickness for warmer climates when it cools down a bit in the evening. This is not a Hawaii print but with the palms and monkeys it give a very tropical feel to this blanket.
I did not use a pattern but just cut two pieces of the flannel the same size and the sewed them together. You can go a simple as you like or more elaborate as shown in the second link. I am planning on sewing more when I find flannel on sale and have them ready for gifts.