01 - Preheat oven to 350°F. Grease and line a 9x5 inch loaf pan with parchment paper.
02 - In a small bowl, combine flour, brown sugar, cinnamon, and salt. Add cold butter and blend with a pastry cutter or fingers until crumbly. Refrigerate until needed.
03 - In a medium bowl, whisk together flour, baking powder, baking soda, and salt. Set aside.
04 - In a large bowl, beat butter and sugar until light and fluffy, about 2–3 minutes.
05 - Add eggs one at a time, beating well after each addition.
06 - Mix in milk, lemon juice, lemon zest, and vanilla extract until fully combined.
07 - Gradually add dry mix to wet ingredients, stirring just until combined to avoid overmixing.
08 - Gently fold blueberries into the batter using a spatula.
09 - Pour batter into prepared loaf pan and smooth the surface. Evenly sprinkle the streusel topping over the batter.
10 - Bake for 50–60 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs.
11 - Allow bread to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before slicing.