Prep: Combine raisins, vanilla and water in a small bowl, let the raisins soak for at least 30 minutes.
75 g raisins , 56 g water, ½ tbsp vanilla extract
Whisk the yeast, sugar and milk in the bowl of your stand mixer and let it bloom until foamy and fragrant, about 15 minutes.
7 g yeast, 75 g milk, 50 g sugar
Strain the raisins: Using a mesh strainer, drain the raisins, pouring the vanilla soaking liquid into the bowl of your stand mixer. Transfer the raisins to a plate lined with paper towels to blot off any excess moisture on the surface.
Make the dough: Add the sourdough discard, egg, flour and salt into the mixing bowl. Using a dough hook, mix the ingredients together at low speed until a shaggy dough forms.
113 g sourdough discard, 1 egg, 6 g salt, 300 g all-purpose flour, 60 g whole wheat flour
Add the butter into the dough one tablespoon at a time, waiting into each piece is absorbed before adding more. The dough will look greasy at first but should gradually look smooth and supple.
28 g butter
Continue kneading with the dough hook on medium speed until a cohesive and smooth, about 3 to 5 minutes. Cover the bowl and let the dough rest for 10 minutes.
With the mixer on medium speed, add the raisins and mix until they are evenly distributed.
Proof the dough: Knead the dough gently with your hands and coax it into a tight ball. Transfer to a lightly-oiled bowl and cover with plastic wrap. Let the dough rise untouched in a warm spot until doubled in volume, about 45 minutes to 1 hour.
Prep: Brush an 8 by 5-inch, light-colored loaf pan with butter, then line with parchment paper (optional). In a small bowl, whisk the cinnamon, sugar and flour together, set aside.
100 g brown sugar, ½ tbsp cinnamon , 4 g all-purpose flour
Shape the dough: Turn the dough out on a lightly floured work surface. Using a rolling pin dusted with flour, flatten the dough into an 8 by 18-inch rectangle.
Using a pastry brush, coat the top of the dough with egg white. Sprinkle the cinnamon sugar in an even layer over the dough, leaving a 1-inch margin.
1 egg white
Working with the shorter side closest to you, roll the dough into a tight cylinder.
Pick up the dough and transfer it to your prepared loaf pan.
Final proof: Cover the loaf pan with plastic wrap and let the dough rise in a warm spot until it almost fills the pan, 30 to 45 minutes.
Prep: Once your dough is almost ready, preheat your oven to 350 F.
Bake the loaf: Brush the top of the dough with the remaining egg white. Bake for 50 minutes to 1 hour, or until the crust is golden brown and the center registers at least 190 F when probed with an instant-ready thermometer.
1 egg white
Enjoy: Transfer the baked loaf to a wire rack. Let the bread cool completely before slicing, about 1 hour.
Storage options: Store any leftover slices in a ziplock bag at room temperature for up to 3 days. For longer term storage, freeze the slices in a ziplock bag for up to 3 months and toast straight from frozen.