Ever wonder where the millions of unsold Parisian croissants go? The shelf life of a croissant is about four hours, which is why bakeries should never be visited after 10am: the croissants become hard, dry, and brittle. But the French, it seems, are very good at recycling. A day's old croissant is more often than not turned into a brand new sugared almond croissant by adding a layer of frangipane, sprinkling with confectioner's sugar, and re-baking. And for those who like sweet pastries, they can be quite tasty. For this tour, I visited the pâtisseries best known for exceptional croissants au beurre, with the thinking that the croissants aux amandes would be equally impressive. In general this held true, though there were a few surprises along the way. I started this journey without a sweet tooth and by the end, finished a few pounds heavier. Warning: this is not a post for dieters.