DH just found me a pair of Northwave winter mtb shoes that I can wear with my Frogs. They are in the UK; same as where I found my winter road shoes. The smallest size is 37, which is what I wear, but it said they run big. I'll take them and wear my thickest socks if I need to.
I rode my Kuota the other day and wore my winter shoes; it's so much easier to just put them on and go instead of dealing with toe warmers, booties, and chemical heaters (I've done all 3 together for temps in the low 30s).
2015 Trek Silque SSL
Specialized Oura
2011 Guru Praemio
Specialized Oura
2017 Specialized Ariel Sport