There is something quietly wonderful about a loaf cake cooling on the counter. The smell of butter, vanilla, and fruit fills the kitchen and makes the day slow down. This blueberry sour cream loaf is simple, tender, and full of flavor. The sour cream keeps it rich and soft, the blueberries add bright sweetness, and the crumbly streusel on top bakes into a golden, crisp layer. It is the kind of bake that feels familiar but still special, the one you make once and then never stop making.

Ingredients

For the Loaf

• ½ cup (115 g) unsalted butter, melted
• 1 cup (200 g) granulated sugar
• 2 large eggs
• ¾ cup (180 g) sour cream
• ¼ cup (60 ml) whole milk
• 1 teaspoon vanilla extract
• 270 g (about 2¼ cups) cake flour
• 1½ teaspoons baking powder
• ½ teaspoon salt
• 1½–2 cups (225–300 g) blueberries, fresh or frozen, not thawed
• 1 teaspoon flour, for tossing the berries

For the Streusel Topping

• ¾ cup (95 g) all-purpose flour
• ½ cup (100 g) brown sugar
• 2 tablespoons granulated sugar
• ½ teaspoon cinnamon (optional)
• 5 tablespoons (70 g) melted butter
• Pinch of salt

Instructions

1. Preheat the oven to 350°F (175°C). Grease a 9×5 inch loaf pan and line it with parchment paper.
2. Make the streusel. Combine flour, brown sugar, granulated sugar, cinnamon, and salt in a small bowl. Drizzle in the melted butter and stir until the mixture forms small crumbs. Set aside.
3. Mix the batter. In a large bowl, whisk the melted butter and sugar until smooth. Add the eggs one at a time and whisk again. Stir in the sour cream, milk, and vanilla until combined.
4. In a separate bowl, whisk together the cake flour, baking powder, and salt. Fold the dry ingredients into the wet mixture until just combined.
5. Toss the blueberries with one teaspoon of flour and gently fold them into the batter.
6. Spoon the batter into the prepared loaf pan and smooth the top. Sprinkle the streusel evenly over the batter and press it lightly so it stays in place.
7. Bake for 50 to 65 minutes, or until a toothpick inserted in the center comes out clean. If the top begins to brown too quickly, cover it loosely with foil.
8. Let the loaf cool in the pan for 10 minutes, then transfer it to a wire rack. When it has cooled completely, dust lightly with powdered sugar if you like.

Notes from the Kitchen

• Cake flour gives this loaf a soft, delicate crumb.
• Whole milk balances the richness of the sour cream without making the batter heavy.
• Frozen blueberries work just as well as fresh. Do not thaw them before baking.
• For a little extra crunch, add ¼ cup of chopped pecans or walnuts to the streusel.
• Skip the glaze. The streusel topping is enough on its own and stays beautifully crisp.

Storage

Keep covered at room temperature for up to two days, or refrigerate for up to five. It freezes well for up to two months. Slice before freezing for easy portions.