Lemon Blueberry Sourdough Coffee (Printable)

Moist squares with bright lemon zest, juicy blueberries, sourdough depth, and a crunchy streusel finish.

# Ingredient List:

→ Cake Batter

01 - 1/2 cup unsalted butter, softened
02 - 3/4 cup granulated sugar
03 - 2 large eggs
04 - 1/2 cup sourdough starter, active or discard
05 - 1 cup whole milk
06 - Zest of 1 lemon
07 - 2 tablespoons fresh lemon juice
08 - 1 teaspoon vanilla extract
09 - 2 cups all-purpose flour
10 - 2 teaspoons baking powder
11 - 1/2 teaspoon baking soda
12 - 1/2 teaspoon fine sea salt
13 - 1 1/2 cups fresh or frozen blueberries, unthawed

→ Streusel Topping

14 - 1/4 cup unsalted butter, cold and diced
15 - 1/3 cup light brown sugar, packed
16 - 1/2 cup all-purpose flour
17 - 1/2 teaspoon ground cinnamon
18 - Pinch of salt

# Directions:

01 - Preheat oven to 350°F. Line a 9-inch square baking pan with parchment paper, allowing excess to overhang the sides for easy removal.
02 - In a small bowl, combine flour, brown sugar, cinnamon, and salt. Add cold diced butter and rub together with fingertips until mixture resembles pea-sized crumbs. Refrigerate until needed.
03 - In a medium bowl, whisk together flour, baking powder, baking soda, and salt. Set aside.
04 - In a large bowl, cream softened butter and sugar until light and fluffy, approximately 2 to 3 minutes. Beat in eggs one at a time until fully incorporated.
05 - Stir in sourdough starter, milk, lemon zest, lemon juice, and vanilla extract until combined. The mixture may appear slightly curdled.
06 - Add dry ingredient mixture to wet ingredients and mix until just combined, avoiding overmixing.
07 - Gently fold blueberries into the batter using a rubber spatula.
08 - Spread batter evenly into the prepared baking pan and smooth the top.
09 - Sprinkle reserved streusel topping evenly over the batter surface.
10 - Bake for 35 to 40 minutes until a toothpick inserted in the center comes out clean and the top is golden brown.
11 - Cool in the pan for 15 minutes. Using the parchment overhang, lift the cake out of the pan and transfer to a wire rack to cool completely before slicing into 12 squares.

# Expert Advice:

01 -
  • Sourdough depth: The sourdough starter — whether discard or active and unfed — adds a gentle tang that elevates the cake far beyond a standard coffee cake.
  • Bright citrus lift: Fresh lemon zest and lemon juice cut through the richness of the butter and eggs, keeping every bite lively and refreshing.
  • Juicy blueberries throughout: Fresh or frozen blueberries pocket themselves into the batter, bursting with sweetness as the cake bakes.
  • That irresistible streusel: Cold butter rubbed into brown sugar, flour, cinnamon, and salt creates a crunchy, golden topping that contrasts beautifully with the soft crumb beneath.
  • Versatile and practical: Equally at home on a brunch table or as an afternoon snack, and easy to slice into neat squares for sharing.
02 -
  • Use cold butter for the streusel: Cold, diced butter rubbed in with your fingertips creates distinct pea-sized crumbs that bake into a properly crunchy topping. Warm butter will produce a paste.
  • Do not overmix the batter: Once the dry ingredients are added, mix only until just combined. Overmixing develops the gluten and results in a tough, dense crumb rather than a tender one.
  • Keep frozen blueberries frozen: Add them directly from the freezer to prevent color bleeding into the batter.
  • Check for doneness with a toothpick: Insert it into the center of the cake — it should come out clean or with just a few moist crumbs. The top should be deep golden and the streusel set.
  • Cool before slicing: Allow the cake to cool completely on a wire rack before cutting into squares to ensure clean edges and a fully set crumb.
  • Parchment overhang is essential: Leaving excess parchment on the sides of the pan makes it easy to lift the entire cake out cleanly without disturbing the streusel topping.
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