This warm double-layer hat has built-in insulating air spaces between the layers. The hat uses two yarns: the inner yarn is the only one that touches the head and it occasionally appears on the public side of the hat. The exterior colour only ever appears on the outside of the hat. The air spaces are creating by working more rounds on the exterior fabric than on the interior layer.
This pattern features detailed written instructions and diagrams.
An eight part Tutorial is available.
See my YouTube clips Simulated In-The-Round DK Swatching Technique and Long-Tail Cast-On:Hints and Tips to help get you started.