Start by preheating your oven to 425°F (220°C). This initial high temperature will give the muffins a nice rise and help create that perfect bakery-style dome.

Line a 12-cup muffin tin with paper liners or grease it with butter or oil. This will ensure the muffins don’t stick and make cleanup easier.

In a large mixing bowl, combine your freshly milled flour, baking soda, baking powder, salt, cinnamon, and pumpkin spice seasoning. Whisk everything together until it’s well blended. This step evenly distributes the leavening agents and spices, ensuring even flavor throughout your sourdough pumpkin spice muffins.

In a separate bowl, whisk together the pumpkin puree, eggs, vanilla extract, honey (or your favorite sweetener), sourdough starter, oil, and kefir or buttermilk. Make sure everything is fully combined and smooth, as this will ensure your muffins have a uniform texture.

Add the dry ingredients to the wet ingredients. Stir gently until just combined. Be careful not to overmix—this will keep your muffins light and fluffy. Allow the batter to rest covered for 15 minutes after mixing.

If you want to bake the muffins the next day, cover the mixed batter and place it in the fridge. The flavors will continue to develop, and you can bake them fresh in the morning. No need to bring the batter to room temperature before baking—simply bake directly from the fridge.

Spoon the batter into the prepared muffin tin, filling each cup to the top for bigger, bakery-style muffins.

Place the muffins in the oven and bake at 425°F (220°C) for 5 minutes. Then, reduce the oven temperature to 350°F (175°C) and bake for an additional 12-15 minutes, or until a toothpick inserted into the center of a muffin comes out clean.

Allow the muffins to cool in the tin for 5-10 minutes before transferring them to a wire rack to cool completely. Serve warm or store them in an airtight container for later.