1. Combine Wet Ingredients: In a large mixing bowl, whisk together the sourdough discard, warm water, granulated sugar, and salt until well combined. The mixture should be slightly bubbly from the discard.

2. Mix in Flour and Add-ins: Gradually add the all-purpose flour, one cup at a time, mixing with a spoon or your hands until a shaggy dough forms. Once the flour is mostly incorporated, add the raisins and cinnamon. Continue to mix until the dough comes together and pulls away from the sides of the bowl.

3. Knead the Dough: Turn the dough out onto a lightly floured surface. Knead for 5-7 minutes until the dough is smooth and elastic. It should spring back when gently poked. If it’s too sticky, add a tiny bit more flour, but be careful not to add too much.

4. Shape the Bagels: Divide the dough into 8 equal pieces. Roll each piece into a smooth ball. Using your thumb, press a hole through the center of each ball, then gently stretch the hole to about 1.5-2 inches in diameter. Place the shaped bagels on a parchment-lined baking sheet.

5. Prepare for Boiling and Baking: Preheat your oven to 400F (200C). Bring a large pot of water to a rolling boil. Add the baking soda and the second tablespoon of granulated sugar to the boiling water. This creates an alkaline bath that gives bagels their signature chewy crust.

6. Boil the Bagels: Carefully drop 2-3 bagels into the boiling water at a time, making sure not to overcrowd the pot. Boil for 30 seconds on each side. Using a slotted spoon, remove the bagels from the water, allowing excess water to drain, and return them to the parchment-lined baking sheet.

7. Add Topping and Bake: If desired, brush the tops of the boiled bagels with the lightly beaten egg white and sprinkle with extra cinnamon sugar. Bake for 20-25 minutes, or until golden brown and cooked through. The bagels should sound hollow when tapped on the bottom.

8. Cool and Serve: Transfer the baked bagels to a wire rack to cool slightly before slicing and serving. They are best enjoyed warm!