1. 1. Prepare Your Wet Ingredients: In a large mixing bowl, combine the sourdough discard, warm milk, 1/4 cup granulated sugar, egg, melted butter, and vanilla extract. Whisk everything together until well combined and smooth. The mixture should be a light, creamy consistency.

2. 2. Combine Dry Ingredients: In a separate medium bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt. Make sure these dry ingredients are thoroughly mixed to ensure even distribution in the dough.

3. 3. Form the Dough: Gradually add the dry ingredients to the wet ingredients, mixing with a wooden spoon or spatula until a shaggy dough forms. Once most of the flour is incorporated, turn the dough out onto a lightly floured surface. Knead for about 5-7 minutes until the dough is smooth and elastic. It should be slightly tacky but not overly sticky.

4. 4. First Rise (Quick Rest): Lightly grease the mixing bowl, place the dough back in, and turn it once to coat. Cover the bowl with plastic wrap or a clean kitchen towel and let it rest in a warm place for 20-30 minutes. This isn’t a long proof, but it helps the dough relax and makes it easier to work with.

5. 5. Prepare Cinnamon Swirl and Shape: While the dough rests, prepare the cinnamon sugar mixture by combining 1/4 cup granulated sugar and 1 tablespoon ground cinnamon in a small bowl. After the rest, gently roll the dough out on a lightly floured surface into a rectangle, roughly 12×8 inches. Brush the melted butter evenly over the dough, then sprinkle the cinnamon sugar mixture over the butter, leaving a small border around the edges.

6. 6. Roll and Place in Pan: Starting from one of the longer sides, tightly roll the dough into a log. Pinch the seam closed to seal. Carefully transfer the log to a lightly greased 9×5-inch loaf pan, seam-side down.

7. 7. Bake the Bread: Preheat your oven to 375 F (190 C). Once preheated, place the loaf pan in the oven and bake for 30-35 minutes, or until the top is golden brown and a wooden skewer or toothpick inserted into the center comes out clean. If the top starts to brown too quickly, you can loosely tent it with aluminum foil.

8. 8. Cool and Glaze (Optional): Once baked, remove the bread from the oven and let it cool in the pan for 10-15 minutes before transferring it to a wire rack to cool completely. If making the glaze, whisk together the powdered sugar, milk/water, and vanilla extract until smooth. Drizzle the glaze over the cooled bread just before serving.