1. 1. Prepare Your Baking Pan and Oven: Start by preheating your oven to 350 F (175 C). Grease and flour a 9×5-inch loaf pan, or line it with parchment paper, leaving an overhang on the long sides to easily lift the bread out later. This prevents sticking and ensures a clean release.

2. 2. Combine Dry Ingredients: In a medium bowl, whisk together the all-purpose flour, baking soda, salt, and 1 teaspoon of ground cinnamon. Make sure there are no lumps and the spices are evenly distributed. Setting these aside ensures they are ready to be incorporated into the wet ingredients.

3. 3. Cream Butter and Sugar: In a large mixing bowl, using an electric mixer or a sturdy whisk, cream together the softened unsalted butter and granulated sugar until the mixture is light and fluffy. This step incorporates air, contributing to a tender crumb. Scrape down the sides of the bowl as needed.

4. 4. Add Wet Ingredients: Beat in the eggs one at a time, mixing well after each addition. Then, stir in the mashed ripe bananas, sourdough discard, and vanilla extract until just combined. Don’t overmix at this stage; a few lumps are perfectly fine.

5. 5. Combine Wet and Dry Mixtures: Gradually add the dry ingredient mixture to the wet ingredients, mixing on low speed or by hand until just combined. Be careful not to overmix the batter; overmixing can lead to a tough bread. Stop as soon as no streaks of flour remain.

6. 6. Create the Cinnamon Swirl: Pour about half of the batter into the prepared loaf pan and spread it evenly. In a small bowl, mix together the 2 tablespoons of granulated sugar and 1 teaspoon of ground cinnamon for the swirl. Sprinkle half of this cinnamon-sugar mixture evenly over the batter in the pan. Top with the remaining batter, spreading it gently, and then sprinkle the rest of the cinnamon-sugar mixture over the top. For a more pronounced swirl, you can gently drag a knife or skewer through the top layer of batter.

7. 7. Bake the Snack Bread: Place the loaf pan in the preheated oven and bake for 50-60 minutes, or until a wooden skewer or toothpick inserted into the center of the bread comes out clean. The top should be golden brown and spring back when lightly touched.

8. 8. Cool and Glaze (Optional): Let the bread cool in the pan for about 10-15 minutes before carefully lifting it out onto a wire rack to cool completely. If you’re making the glaze, whisk together the powdered sugar, milk, and vanilla extract until smooth. Drizzle the glaze over the cooled bread just before serving.