Creating your Sourdough Blueberry Coffee Cake is straightforward. Just follow these simple steps for an incredible result:

1. Preheat the Oven: Preheat your oven to 350°F (175°C). Grease a 9-inch round cake pan or line it with parchment paper.

2. Cream Butter and Sugar: In a mixing bowl, beat the softened butter and granulated sugar together until light and fluffy.

3. Add Eggs and Vanilla: Incorporate the eggs one at a time, adding the vanilla extract as you mix until fully combined.

4. Mix In Sourdough: Add your bubbly sourdough starter to the mixture, blending well until there are no lumps.

5. Combine Wet Ingredients: Pour in the buttermilk and stir gently until just blended.

6. Whisk Dry Ingredients: In a separate bowl, whisk together the flour, baking powder, baking soda, and salt.

7. Combine Mixtures: Gradually add the dry mixture to the wet ingredients, folding gently until just combined. Avoid overmixing.

8. Prepare Blueberries: Toss the blueberries in a tablespoon of flour to prevent them from sinking during baking.

9. Fold in Blueberries: Carefully fold the flour-coated blueberries into the batter.

10. Pour Batter into Pan: Transfer the batter into the prepared cake pan, spreading it evenly.

11. Bake: Place in the oven and bake for 35-40 minutes, or until a toothpick comes out clean.

12. Cool: Once baked, let the cake cool in the pan for about 15-20 minutes before transferring it to a wire rack to cool completely.