01 - Preheat oven to 375°F. Line a 12-cup muffin tin with paper liners or grease lightly with cooking spray.
02 - In a large bowl, whisk together flour, sugar, poppy seeds, baking powder, baking soda, and salt until well blended.
03 - In a separate medium bowl, whisk eggs, milk, melted butter, lemon juice, lemon zest, and vanilla extract until smooth and emulsified.
04 - Pour wet ingredients into dry ingredients. Using a spatula, fold gently until just combined—batter should remain slightly lumpy. Avoid overmixing to prevent tough muffins.
05 - Divide batter evenly among prepared muffin cups, filling each about three-quarters full. Use an ice cream scoop for consistent portioning.
06 - Bake for 18 to 20 minutes until golden brown and a toothpick inserted into the center comes out clean.
07 - Let muffins cool in the tin for 5 minutes before transferring to a wire rack. Cool completely before storing or serving.