Regular old beanie hat, fleece beanie, light balaclava, or a combo of one or more of them. I have a bomber hat I made with leftovers from a Ray Way kit - it's tooooo hot for me. Breathable seems to work better for me anyway. Been down to low 20s with the balaclava as a neck/lower face cover and a fleece beanie.

JRB makes down hood/sleeves to go with their wearable quilts.
"In the beginner's mind there are many possibilities. In the expert's mind there are few." Shunryu Suzuki