Lemon Blueberry Sourdough Squares

These Lemon Blueberry Sourdough Coffee Cake Squares are the perfect marriage of tangy citrus, juicy berries, and the subtle complexity of sourdough. With a moist, tender crumb and a buttery cinnamon streusel topping that adds irresistible crunch, these squares are ideal for weekend brunch gatherings or a sweet afternoon pick-me-up with coffee. The addition of sourdough starter not only reduces waste but also adds a gentle tang that beautifully complements the bright lemon and sweet blueberries.

Save to Pins

What makes this coffee cake truly special is the versatility of sourdough starter. Whether you're using active starter or discard, it adds moisture and a subtle tanginess that elevates these squares beyond ordinary coffee cake. The fresh blueberries burst with sweetness in every bite, while the lemon zest brightens the entire flavor profile. Baked in a square pan and cut into portions, this recipe is perfect for serving a crowd or enjoying throughout the week.

Ingredients

• Cake Batter: 120 g (½ cup) unsalted butter, softened; 150 g (¾ cup) granulated sugar; 2 large eggs; 120 g (½ cup) sourdough starter (discard or active, unfed); 240 ml (1 cup) whole milk; Zest of 1 lemon; 2 tbsp fresh lemon juice; 1 tsp vanilla extract; 250 g (2 cups) all-purpose flour; 2 tsp baking powder; ½ tsp baking soda; ½ tsp fine sea salt; 200 g (1½ cups) fresh blueberries (or frozen, unthawed)
• Streusel Topping: 50 g (¼ cup) unsalted butter, cold and diced; 65 g (⅓ cup) light brown sugar, packed; 65 g (½ cup) all-purpose flour; ½ tsp ground cinnamon; Pinch of salt

Instructions

Step 1: Prepare the oven and pan

Preheat oven to 180°C (350°F). Line a 23cm (9-inch) square baking pan with parchment paper, leaving an overhang for easy removal.

Step 2: Make the streusel

In a small bowl, combine flour, brown sugar, cinnamon, and salt. Add cold butter and rub with fingertips until the mixture forms pea-sized crumbs. Refrigerate until needed.

Step 3: Combine dry ingredients

In a medium bowl, whisk together flour, baking powder, baking soda, and salt.

Step 4: Cream butter and sugar

In a large bowl, cream the butter and sugar until light and fluffy, about 2-3 minutes. Beat in eggs one at a time.

Step 5: Add wet ingredients

Stir in sourdough starter, milk, lemon zest, lemon juice, and vanilla until combined (the mixture may look slightly curdled).

Step 6: Mix the batter

Add the dry ingredients to the wet ingredients and mix until just combined.

Step 7: Fold in blueberries

Gently fold in blueberries.

Step 8: Assemble

Spread the batter evenly into the prepared pan. Sprinkle streusel topping evenly over the batter.

Step 9: Bake

Bake for 35-40 minutes or until a toothpick inserted into the center comes out clean and the top is golden brown.

Step 10: Cool and serve

Cool in the pan for 15 minutes, then lift out using parchment and cool completely on a wire rack before slicing into squares.

Zusatztipps für die Zubereitung

For best results, ensure your butter is properly softened for the cake batter but cold for the streusel—this contrast is key to achieving both a fluffy cake and a crumbly topping. If the batter looks slightly curdled after adding the sourdough starter and lemon juice, don't worry; this is normal due to the acidity and will not affect the final texture. When folding in blueberries, be gentle to avoid crushing them and turning the batter purple. If using frozen blueberries, do not thaw them first as this prevents excess moisture and color bleeding. For easier slicing, allow the cake to cool completely and use a sharp knife wiped clean between cuts.

Varianten und Anpassungen

This recipe is wonderfully adaptable to your taste preferences and what you have on hand. For a nutty twist, add ½ cup chopped toasted pecans to the streusel for extra crunch and richness. If you'd like a different citrus profile, substitute part of the lemon juice with lime for a more tropical flavor. Raspberries or blackberries can replace the blueberries for a different berry experience. For a dairy-free version, use plant-based butter and your favorite non-dairy milk. You can also reduce the sugar slightly if you prefer a less sweet cake, or add a simple lemon glaze on top for extra sweetness and visual appeal.

Serviervorschläge

These coffee cake squares are delightful served slightly warm with a pat of butter melting on top, or at room temperature alongside your morning coffee or afternoon tea. For a more indulgent presentation, serve with a dollop of whipped cream or Greek yogurt and a drizzle of honey. They pair beautifully with fresh fruit salad for a complete brunch spread. Store leftovers in an airtight container at room temperature for up to 3 days, or refrigerate for up to a week. These squares also freeze exceptionally well—wrap individual portions in plastic wrap and freeze for up to 3 months, then thaw at room temperature or warm briefly in the microwave.

Save to Pins

These Lemon Blueberry Sourdough Coffee Cake Squares are a testament to how simple ingredients can create something truly special. The combination of tangy sourdough, bright citrus, and sweet berries makes every bite a delightful experience. Whether you're serving them at a brunch gathering, packing them for a picnic, or simply enjoying one with your morning coffee, these squares are sure to become a beloved favorite in your baking repertoire.

Frequently Asked Questions

→ Can I use frozen blueberries?

Yes, frozen blueberries work well. Fold them in directly without thawing to prevent excess moisture.

→ What does the sourdough starter add to the squares?

Sourdough starter introduces subtle depth and tang, enhancing the overall flavor and texture of the squares.

→ How should I store the squares to keep them fresh?

Store in an airtight container at room temperature for up to 3 days or refrigerate for longer freshness.

→ Can I substitute the streusel topping?

Yes, alternatives like chopped nuts or oats can be added for different textures and flavors.

→ Is it possible to add nuts to this dish?

Absolutely, try adding chopped toasted pecans to the streusel for a nutty twist.