One my favorite parts of living here are the amazing bakeries on every block. Not only is the bread wonderful (never shall I buy sliced bread in plastic bags again!), but all around the year they feature various traditional pastries for a limited time only.
The first year here we got addicted to panellets, and I had gotten to the point where I needed my daily fix. Then all of a sudden, they all disappeared! There are stores in Barcelona that specialize in all kinds of crazy custom panellets shaped like mice and pumpkins, etc.