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. Set aside.
03 - In a large bowl, beat softened butter and granulated sugar together until light and fluffy, approximately 2 minutes.
04 - Add eggs one at a time, beating thoroughly after each addition. Blend in lemon juice, lemon zest, and vanilla extract until fully incorporated.
05 - Add dry ingredients to wet mixture in three additions, alternating with milk. Begin and end with dry ingredients. Mix until just combined—avoid overmixing to maintain texture.
06 - Distribute batter evenly among prepared cupcake liners, filling each approximately two-thirds full.
07 - Bake for 16 to 18 minutes, or until a toothpick inserted into the center emerges clean.
08 - Allow cupcakes to rest in the pan for 5 minutes, then transfer to a wire rack to cool thoroughly before frosting.
09 - Beat softened butter and cream cheese until smooth and creamy. Gradually incorporate sifted powdered sugar, mixing well after each addition. Blend in lemon juice, lemon zest, and salt until smooth.
10 - Once cupcakes have cooled completely, generously frost with lemon cream cheese frosting. Optionally garnish with additional lemon zest or poppy seeds.