Can I find these delicious cookies in just about any supermarket in Paris or do I need to go someplace in particular?
The specific packaging does not look familiar, but St. Michel butter galettes are everywhere in French supermarkets, and various other brands too. Besides galettes, I also suggest trying Palets bretons, a bit like shortbread.
Yes, Galette Saint Michel are an industrial product sold for a few euros in all supermarkets and grocery stores.
We love them and I buy a couple of boxes a week when we are in Paris. they are packaged in a series of separate packs of 3 and so they are also convenient for snacks or picnics when you are traveling around. In literally every grocery store.