Scottish shortbread or Brittany cookie?

They're both shortbread with a couple differences though.
The Scottish shortbread doesn't contain egg. It is made of butter, sugar and flour which makes it melt in your mouth.
The Brittany cookie contains egg and a magical ingredient: salted butter (using anything else than salted butter in Brittany is a sacrilege considered as an act of grand treason against gastronomy). Brittany cookies are still crumbly like a shortbread but with that little cake-i-er texture brought by the addition of eggs in the recipe. Hence the more yellow tone too.