In previous winters on long distance rides I’ve used Oxford Bone Dry muffs and summer gloves, the combination worked well and I found the Oxford Bone Dry muffs do exactly what they say on the box, bone dry and warm.
Some points to note - You need to be careful how you fit them, get them at the wrong angle and they can fill up with rain water, they keep it in as well as out! I found I had to fit lever guards to prevent the muffs from folding in on themselves against the backs of my hands reducing thermal efficiency, also without the lever guards at motorway speeds the muffs can fold back and apply light pressure to the brake and clutch levers. The Oxford muffs are big and with a large tank bag there is some interference to full steering lock.
I’m leaving them off this winter in favour of a pair of cheap as chips (£20) hand guards off Amazon and my trusty old Frank Thomas Aqua winter gloves which are similar to these below but without the hard knuckle armour. A top spec winter glove you can try on down at a J&S store near you.