Preheat your oven to 425F (220C) and line a 12-count muffin pan with muffin liners or grease with nonstick spray.
To make the streusel, toss together the all-purpose flour, butter, and brown sugar in a small bowl. Set aside.
In the bowl of a stand mixer or using a handheld mixer cream together the granulated sugar, butter, and brown sugar at medium-high speed for 4 minutes until pale and fluffy.
Add the eggs, buttermilk, vanilla extract, lemon juice, and lemon zest. Beat for one minute on medium speed until everything is combined and smooth. Scrape down the sides of the bowl as needed.
In another large bowl, combine the flour, baking powder, baking soda, and salt. Add the wet ingredients to the dry ingredients and combine them using a whisk. Whisk only until all the dry ingredients are wet and everything is combined. Don’t overmix!
Fold in the raspberries with a rubber spatula.
Divide the batter between the 12 muffin tins and fill the tins all the way to the top. Top with streusel.
Bake for 5 minutes at 425F (220C) then lower the temperature to 350F (180C) and bake for 18 to 20 more minutes. The muffins are done when a skewer comes out clean.