SWEET SOURDOUGH PREFERMENT. In a tall jar or large container with a lid, mix the bread flour, whole wheat flour, sugar, water, and mature sourdough starter with your hand or a fork. Ensure that no dry flour remains at the bottom of the jar. Cover the container and let it rest at room temperature (ideally between 70° and 80°F) for 4 hours. It should double in size and have a firm, bubbly structure on the top. Once the preferment is ready to use, you can start baking straight away or place it in your fridge for later use (up to 2 days).

DOUGH. In a microwave-safe bowl, combine the chocolate chips and milk and heat in the microwave for 2 to 3 minutes so that the chocolate starts to melt. Remove and let rest for 10 minutes. Whisk together to create a slurry. Note that this mixture w ill not be thick; it should be slightly runny. In the bowl of a stand mixer with the dough hook attachment, add the chocolate mixture, all-purpose flour, bread flour, sugar, and sourdough preferment and mix on low speed until a rough dough for ms, 3 to 4 minutes. Increase the mixer to medium speed, add half of the softened butter, and mix for 2 to 3 minutes or until the butter gets fully incorporated. Add the remaining softened butter and mix again until the dough smooths out.

Add the salt, trickle in the water, switch the mixer to high speed, and mix for 3 to 4 minutes until all the water is incorporated and there’s a smooth and elastic dough. Transfer to a clean, lightly oiled bowl and cover. Let ferment at room temperature for 4 hours. After the initial fermentation period, divide the dough into twelve 100-g pieces (about the size of small lemons) and shape each piece into a tiny log. Cover and let the dough rest for 15 minutes. To shape the mallorca, roll out each log to about 10 inches long and brush liberally with the melted butter. Roll the dough into a spiral shape and place on a parchment-lined Holy Sheet. Let the dough proof at room temperature for 4 hours. The best way to proof them is to just leave them in the oven (not turned on, of course). Remove the mallorcas from the oven before preheat ing, if you proofed them in the oven, and preheat the oven to 375°F. In a small bowl, mix the egg and the pinch of salt, brush the mallorcas with the egg wash, place the sheet pan in the oven, and bake for 20 minutes.

TO MAKE THE GLAZE, heat the guava paste in a small saucepan on medium heat for about 5 minutes, or until it breaks down and has the consistency of thick jelly — be careful not to touch the guava when hot! Set aside briefly and let cool for 5 minutes. In the bowl of a stand mixer with the paddle attachment, add the guava paste, butter, powdered sugar, and heavy cream and mix on medium speed until creamed together and slightly runny. When the mallorcas are baked, cool on Big Chill, glaze, dust with powdered sugar, if desired, and serve.