-
Preheat the oven to 375 degrees F.
-
Grease a 9 by 5 inch loaf pan.
-
In a small mixing bowl, combine 1/4 cup of the sugar, brown sugar, 1/3 cup flour, 4 tablespoons butter, and 1/2 teaspoon cinnamon. Mix until the topping is incorporated.
-
Using an electric mixer, cream the remaining sugar and butter together. Add the egg, 1/2 and 1/2, sour cream , and lemon juice, blend until smooth.
-
In a mixing bowl, sift the remaining flour, baking powder, salt and remaining cinnamon together. With the machine running, slowly add the flour until all the flour is incorporated.
-
Fold in the blueberries and lemon zest. Pour the batter into the prepared pan. Sprinkle the topping on top of the batter.
-
Bake the bread for about 50 minutes, or until the top is golden brown. Remove the pan from the oven and cool for 5 minutes. Remove the bread from the oven and cool on a wire rack. Slice and serve.