Preheat oven to 350ºF (180°C).
Butter or use baking spray to grease an 20x30cm (8x11-inches) rectangular pan.
Sift 2 cups flour, 2 teaspoons baking powder and ¼ teaspoon salt. Set aside. Or have the ingredients measured and sift them directly over the batter.
In a large bowl, beat 1 cup butter until creamy. Slowly add 1 and ¼ cups sugar and beat for 2 minutes.
Add 2 eggs one at a time, beating well after each addition.
Add 1 teaspoon lemon zest and 1 and ½ teaspoons vanilla.
Beginning and ending with dry ingredients, add them in 3 parts alternating with the sour cream in 2 parts.
Pour half the batter into the prepared pan and smooth the top.
Scatter 1 cup raspberries over the batter and sprinkle with the brown sugar.
Mound the remaining batter on top. Don’t pour it all in one place, or it will be more complicated to smooth out.
With an offset spatula or the back of a spoon, spread the batter carefully, trying not to disturb the berries much. If it gets slightly stained, that’s fine. The batter will cover the raspberries.
Bake for about 45 minutes, or until a cake tester or toothpick inserted in the center comes out clean.
Let cool on a wire rack for 15 minutes, then carefully run a smooth-bladed knife around the edges to loosen any stuck parts. Let cool completely before glazing.