# What You Need:
→ Muffins
01 - 1 cup (120g) all-purpose flour
02 - 1 cup (125g) whole wheat flour
03 - 1 cup (200g) granulated sugar
04 - 1 teaspoon baking powder
05 - 1/2 teaspoon baking soda
06 - 1/2 teaspoon salt
07 - 2 large eggs
08 - 1/2 cup (4 fluid ounces) vegetable oil or melted butter
09 - 1 cup (240g) sourdough discard (unfed)
10 - 1/2 cup (4 fluid ounces) whole milk
11 - 1 teaspoon vanilla extract
12 - Zest of 1 large lemon
13 - 2 tablespoons fresh lemon juice
14 - 1 1/2 cups (225g) fresh or frozen blueberries
→ Crumb Topping
15 - 1/2 cup (65g) all-purpose flour
16 - 1/3 cup (65g) light brown sugar
17 - 1/4 cup (2 ounces) unsalted butter, cold and cubed
18 - Pinch of salt
19 - Zest of 1/2 lemon
# Steps:
01 - Preheat oven to 375°F (190°C). Line a 12-cup muffin tin with paper liners or grease thoroughly.
02 - In a medium mixing bowl, whisk together both flours, granulated sugar, baking powder, baking soda, and salt until evenly distributed.
03 - In a large mixing bowl, whisk together eggs, oil, sourdough discard, milk, vanilla extract, lemon zest, and lemon juice until thoroughly combined.
04 - Gradually fold the dry ingredient mixture into the wet mixture using a spatula until just combined, being careful not to overmix the batter.
05 - Gently fold in the blueberries using a spatula, distributing them evenly throughout the batter. If using frozen berries, do not thaw them beforehand.
06 - Divide the batter evenly among the muffin cups, filling each approximately 3/4 full to allow room for rising.
07 - In a small bowl, combine all-purpose flour, light brown sugar, cold cubed butter, salt, and lemon zest. Using your fingertips or a pastry cutter, blend until the mixture resembles coarse breadcrumbs.
08 - Sprinkle the crumb topping generously over each muffin, distributing it evenly across all cups.
09 - Bake for 22 to 25 minutes, or until a toothpick inserted into the center of a muffin comes out clean and the tops are golden brown.
10 - Cool the muffins in the tin for 5 minutes, then transfer them to a wire cooling rack to cool completely.