01 - Preheat oven to 350°F. Line a 12-cup muffin pan with paper liners.
02 - In a medium bowl, whisk together flour, poppy seeds, baking powder, baking soda, and salt until well blended.
03 - In a large bowl, beat softened butter and granulated sugar until light and fluffy, approximately 2 minutes.
04 - Add eggs one at a time, mixing thoroughly after each addition. Blend in lemon juice, lemon zest, and vanilla extract.
05 - Gradually add dry ingredients to wet mixture in three portions, alternating with milk. Begin and end with dry ingredients. Mix until just incorporated, being careful not to overmix.
06 - Distribute batter evenly among prepared liners, filling each about two-thirds full.
07 - Bake for 16 to 18 minutes until a toothpick inserted into the center comes out clean.
08 - Let cupcakes rest in the pan for 5 minutes, then transfer to a wire rack to cool entirely before frosting.
09 - Beat butter and cream cheese together until smooth. Gradually incorporate powdered sugar, mixing well. Stir in lemon juice, lemon zest, and salt until combined.
10 - Generously frost cooled cupcakes with lemon cream cheese frosting. Optional garnish: sprinkle with additional lemon zest or poppy seeds.