Things I have learnt with my limited experiments with trying to make Breton galettes (savory crepes) so far:
1. Liquid batter: The more liquid-y the batter, the more bubbles created when the batter hits the hot pan. I would dilute the batter to the consistency of somewhere between heavy cream and full-fat milk.
2. Hot pan: Need pan to be quite hot to induce the bubbles when batter is poured onto the pan. I keep it around med-high, and lower it slightly only as the galette is almost done
3. Mucho butter on pan: Copious amount of butter on hot pan isFull key to a crispy galette. But in the end, crispiness will reduce significantly when galette cools. So more butter may-may not be needed upon re-heating
4. 100% buckwheat batter didn't work for me, as galette became so fragile. 50/50 with AP flour worked for me. Adding 1 egg per 1 cup of flour also helped keep batter together. Next time, may want to try keeping batter overnight to strengthen the bonds.