01 - Preheat the oven to 350°F. Grease and flour a 9x5-inch loaf pan or line it with parchment paper.
02 - Combine flour, sugar, lemon zest, and cold butter in a small bowl. Use fingers or a pastry cutter to blend until coarse crumbs form. Refrigerate until needed.
03 - Whisk flour, baking powder, baking soda, and salt in a medium bowl. Set aside.
04 - In a large bowl, beat softened butter and granulated sugar until light and fluffy, about 2 to 3 minutes.
05 - Add eggs one at a time, beating well after each addition. Stir in milk, lemon juice, lemon zest, and vanilla extract until combined.
06 - Gradually add dry ingredients to wet ingredients, mixing just until incorporated.
07 - Gently fold in the blueberries, ensuring even distribution without overmixing.
08 - Pour batter into prepared loaf pan, smooth the surface, and sprinkle streusel topping evenly over the batter.
09 - Bake for 50 to 55 minutes or until a toothpick inserted into the center comes out clean. Tent with foil during the last 15 minutes if the top browns too quickly.
10 - Allow to cool in the pan for 15 minutes, then transfer to a wire rack to cool completely before slicing.