Preheat your oven to 350°F (177°C). Line a 9x5-inch loaf pan with parchment paper, leaving enough overhang on the sides to easily lift the loaf out after baking.

In a small bowl, combine the flour and brown sugar. Add the grated, very cold butter and use a fork or your fingertips to work the butter into the dry ingredients until coarse, crumbly pieces form. Place the crumble in the refrigerator while you prepare the batter.

In a medium mixing bowl, whisk together the flour, baking powder, and salt until evenly combined. Set aside.

In a large mixing bowl, whisk together the melted butter and granulated sugar until well combined.

Add the eggs and whisk until the mixture becomes smooth and slightly lighter in color.

Whisk in the vanilla extract, Greek yogurt, and sourdough discard until fully incorporated and smooth.

Gradually add the dry ingredients to the wet ingredients, gently folding with a spatula until just combined. Be careful not to overmix, as this can result in a dense loaf. A few small streaks of flour are perfectly fine.

In a separate bowl, toss the fresh blueberries with the remaining 2 tablespoons of flour until evenly coated. This helps prevent the berries from sinking during baking.

Gently fold the coated blueberries into the batter until evenly distributed.

Pour the batter into the prepared loaf pan and spread it into an even layer.

Scatter several additional fresh blueberries over the top of the batter.

Evenly sprinkle the prepared crumble topping over the blueberries.

Bake for 50–60 minutes, or until the top is golden brown and a toothpick inserted into the center comes out clean or with just a few moist crumbs attached.

If the crumble begins browning too quickly, loosely tent the loaf with aluminum foil during the final 15–20 minutes of baking.

Allow the loaf to cool in the pan for about 15–20 minutes, then use the parchment paper to carefully lift it onto a wire rack to cool slightly.

In a small bowl, whisk together the powdered sugar, vanilla extract, and 1 tablespoon of milk until smooth. Add additional milk, a little at a time, until your desired drizzling consistency is reached.

Drizzle the icing over the slightly warm or completely cooled loaf.

Slice and enjoy!