You cannot go wrong with the product from any of the coffeeshops mentioned above. I would also include the Grey Area, Dampkring, and Barneys.

Also, you can still get space cakes, etc. The Chocolata coffeeshop on Spuistraat used to carry a complete line of cakes, bon bons, brownies, etc. It has been taken over by the Abraxas coffeeshop. The original Abraxas sells brownies, muffins, cakes and shakes all with your favorite active ingredient, so I would assume this location will also carry the same.