I think the best way would be to have some capable Queen-Regents who manage to start filling the corridors of power, and combine it with circumstances that make HER preferable to HIM.
I litterally can't name all women having positions of powers, being regents or rulers of their own, in all the Middle-Ages. Listing the most famous exemples alone would take too much time.
So, let's remember that, again, women didn't have to proove their worth to men, because they did it on a regular base. What changed is that having women in charge became less and less tolerable by the XVIth century for a political society bred on Roman Law. Almost every woman searching a position of power got an immediate reputation as scheming monsters; and women that did before either conveniently forgotten or described as bad exemple.
Joan of Arc surviving the 100 years war and the monarch dying could lead to her being declared a form of Monarch, with enough victories under her belt. Bring in a few pious women in as generals in her own image, and women could change France entirely.
It's not really going to happen, altough for much different reasons than sexism.
1) Charles VIII already had children at this point.
2) Joan of Arc didn't led victories herself, and while she had commending skills, most of victories in the 1430's were engineered by other peoples, Joan leading as a banner (on both definitions of the word)
3) Joan being of low nobility, even disregarding 1 and 2, there's no way in Hell or Heaven that she would have been chosen and accepted.
And that's only the top of it. It could make a nice ASB TL, but nowhere close to happening otherwise.
Or flip the 100 years war result - have the British win
HYW was basically unwinnable for England if the goal is to swallow up France.
At worst, it would have turned into a war of attrition, and while France had really divided periods up to civil war, it beneficied from quite ressources (demographic, economics, military, etc.) that England did catched up but with a Parliment not too enthuiast about it.
There's a reason why the war lasted decades, or why Plantagenets preferred to make truces and peace of compromise as Brétigny as more realistic objectives while they clearly had the upper hand, over taking over the french crown with dubious rights.
Even if, by sheer luck, Double Kingship manages to be a thing, having Queen ruling it would certainly never influences history that much : again, you had countless Queen and regents ruling with particularily sharp political skills in both France and England historically, and it did peanuts to ensure a slighly less obvious gender pressure on women after the XVIth.