• Gather your ingredients so that you have everything close at hand on the counter or table. Using a knife and cutting board, chop raisins into small pieces.

Prepare the Dough

• In a large mixing bowl and using a dough hook, mix together the fed sourdough starter, warm water, softened butter, granulated sugar, instant dry milk, kosher salt, and instant yeast.
• Add in 2 1/2 cups of the all-purpose flour along with the chopped raisins. Mix to combine. Knead the dough 5-7 minutes, using as much of the remaining cup of all-purpose flour as needed to form a smooth dough. Transfer dough to a greased bowl and cover with plastic wrap that has been sprayed with baking spray. Allow to rise until doubled, about 60-90 minutes.
• (If you have opted not to include the instant yeast, you will need to go through the stretch and fold process every 30-40 minutes to build up the natural gluten in the dough. You should also expect longer rising times.)
• At this point, you may refrigerate the dough until ready to use, up to 24 hours, or continue on to the next step.

Make the Cinnamon Filling

• Remove the dough from the refrigerator and allow to set out for 40-60 minutes. Spray a 10"x5" loaf pan with baking spray. Preheat oven to 350℉.
• Prepare egg wash by whisking together 1 small to medium egg with 2 tablespoons water. Set aside until ready to use.
• In a small bowl, whisk together the granulated sugar, all-purpose flour, and ground cinnamon.

Shape the Dough

• Place dough on a lightly floured surface and pat out into a 10" x 18" rectangle. You may use a rolling pin for this, if desired.
• Using a pastry brush, spread the egg wash over the dough. Then generously sprinkle the dough with the cinnamon mixture up to an inch from the edges. Starting at one short edge, firmly roll the dough into a log, pinching the edges and ends to seal.
• Place the dough seam side down into the prepared loaf pan. Allow to rise 60-90 minutes until it is puffy and has nearly doubled.

  (If you've opted not to include instant yeast, your rising time may be 2-3 hours, depending on the room temperature.)
• Bake in preheated oven for 40-50 minutes, until loaf is golden brown. Remove from oven and turn bread out onto a wire rack to cool. Makes 1 loaf.