Preheat oven to 425°F. Line a muffin tin with cupcake liners.
Combine flour, poppyseeds, baking powder, baking soda, and salt in a large bowl, whisking to combine.
In a separate bowl whisk butter, 3/4 cup sugar, and brown sugar until smooth. Add in eggs, one at a time, whisking until combined.
Add the milk, sour cream, vanilla, lemon juice, and 2 tsp lemon zest and whisk until smooth.
Create a well in the center of the dry ingredients; fold in wet ingredients to dry ingredients until just combined. Fill each muffin cup 3/4 of the way full with prepared batter.
In a small bowl combine remaining 1/4 cup sugar and 1 tsp lemon zest. Rub lemon zest and sugar granules together, using your fingers, for about 30 seconds. Sprinkle each muffin with lemon sugar.
Bake muffins 5 minutes at 425°F, reduce temperature to 350°F, and bake additional 12 to 14 minutes or until edges are lightly golden brown.
Let muffins cool completely in pan before transferring to a wire rack to cool completely. Serve warm and store in an airtight container in the refrigerator 7 to 10 days.