Stir lemon juice into milk and set aside while measuring out other ingredients.
Heat oven to 400 F/205 C. Line muffin tin with 12 baking cups (cupcake liners)
Remove 1.5 tbsp from the 2 cups of flour and set aside to coat raspberries.
Place remaining all purpose flour (2 cups minus 1.5 tbsp) in a large bowl. Add baking powder, salt and whisk well.
Add eggs to another bowl and whisk well. Whisk in sugar and melted butter. Add milk, vanilla extract and lemon zest. Whisk to combine.
Add wet ingredients to dry ingredients and stir to combine. Gently toss raspberries with reserved tbsp of flour. Gently fold raspberries into batter. Use an ice cream scoop to evenly distribute batter into 12 muffin cups.
To make streusel, with a fork, mix flour, brown sugar and white sugar. Mix in melted butter. Crumble streusel on top of the batter and press lightly so it adheres to batter. Bake in the heated oven for 23-25 minutes or until a toothpick inserted into the middle of the muffin comes out clean. Cool on a rack. Can be served slightly warm or when completely cool.