On a recent pastry reconnaissance in Montreal, I discovered a unique treat at Patisserie La Gascogne - a city landmark. Thick rounds of brioche coated with almonds and a custardy topping. Delicious. The only possible hitch is finding a round bread mold. I used baguette molds, regular bread pans, and coffee cans to make this. Use what you have - don't sweat it. This recipe is true Paris fare. Most books on Paris cuisine feature a version of the Bostok. Don't be dissuaded by the length of the recipe. It's well worth the effort.