1. Lightly grease a large bowl or proofing tub with extra-virgin olive oil.
2. In the bowl of a stand mixer, add the warm water.
Add the softened butter (it’s important the butter is soft to ensure it mixes well) and mix with a wooden spoon. The butter won’t dissolve, but it should be very soft.
3. Add the flour, yeast, sugar, and salt.
Mix on a low speed for 5 to 10 minutes until the dough is silky and slightly elastic. With wet hands, lift the dough and shape into a smooth ball before transferring it to your oiled bowl or proving tub. Cover with plastic wrap or an airtight lid. Proof for 2 hours, or until it doubles in size.
4. Grease the flat pan with butter, then scatter a thin layer of fine semolina flour over the top.
Remove the packaging on the Camembert and place it in the center of the pan. Cut a few deep slices across the center of the cheese, then insert small sprigs of rosemary.
5. On a lightly floured surface, use a scale to divide and weigh the dough into 3 equal pieces.
Stretch each piece out into narrow strips roughly 24 inches (60 centimeters) long. Lay the pieces side by side and begin plaiting the dough: Cross the right strand over the middle strand, then cross the left strand over the now-middle strand. Continue the braid, alternating right and left strands.
6. Once the plait is finished, curl it around the Camembert on the tray.
(If you have excess dough, cut the overlapping section and bake it on its own as a snack.) Pinch the ends together to form a closed wreath around the cheese.
7. In a small bowl, mix the egg and a teaspoon of water to make an egg wash.
8. Brush the dough with the egg wash, then sprinkle sesame seeds over the surface.
9. Cover the dough with a large bowl or deep tray, or place inside a plastic bag with the end folded over to keep any air out.
Let the dough proof for 30 minutes.
10. Fire up your oven, aiming for 625° F (330° C) on the baking stone inside.
Aim the thermometer at the center of the stone to quickly and accurately check the temperature.
11. Place the tray in the oven and turn off the gas, or, if using wood or charcoal, close the baffle to dampen the flames.
12. Cook for 9 minutes in the residual heat, rotating the pan 180 degrees halfway through.
13. If cooking with gas, return the oven to its lowest setting.
If cooking with wood or charcoal, open the baffle, but maintain a low flame, using a charcoal bed if possible. Cook for 9 more minutes, making sure to turn the pan every 2 to 3 minutes. The dough should puff up, start to smell delicious, and turn a deep golden brown.
14. Remove the tray and spoon cranberry sauce onto the melted cheese.
