Step 1

Preheat oven to 350ºF (180°C).

Step 2

Butter or use baking spray to grease an 20x30cm (8x11-inches) rectangular pan.

Step 3

Mix 1 cup blueberries with 2-3 tablespoons of flour from the 2 cups. Reserve.

Step 4

Sift the remaining flour, baking powder and salt. Set aside. Or have the ingredients measured to sift them directly over the batter when instructed.

Step 5

In a large bowl, beat the soft butter until creamy. Slowly add sugar and beat 2 minutes.

Step 6

Add eggs one at a time, beating well after each addition.

Step 7

Add the lemon zest and vanilla.

Step 8

Beginning and ending with dry ingredients, add them in 3 parts, alternating with the sour cream in 2 parts.

Step 9

Add the reserved floured blueberries and stir with a spatula, integrating well until no flour spots remain. Don’t beat or crush the blueberries.

Step 10

Pour the batter into the prepared pan and smooth the top.

Step 11

Scatter the remaining 1/2 cup blueberries over the batter. Sprinkle with the brown sugar.

Step 12

Bake for about 45 minutes or until a cake tester or toothpick inserted in the center comes out clean.

Step 13

Let it cool on a wire rack for 15 minutes, and run a smooth-bladed knife carefully around the edges to loosen any stuck parts.

Step 14

Let cool completely before glazing.

Step 15

Mix powdered sugar with 2 tablespoons of lemon juice in a medium bowl until smooth. Add more juice if needed, 1 teaspoon at a time, until it’s like thick honey.

Step 16

Drizzle on top of the cooled cake.

Step 17

Let dry, cut into squares and serve.