01 - Preheat oven to 375°F. Line a 12-cup muffin tin with paper liners or grease lightly.
02 - In a large bowl, whisk together the flour, sugar, poppy seeds, baking powder, baking soda, and salt until evenly mixed.
03 - In a separate bowl, whisk the whole milk, melted butter, eggs, sour cream, lemon zest, and vanilla extract until fully combined.
04 - Pour wet ingredients into dry ingredients and gently fold until just combined; avoid overmixing to maintain tenderness.
05 - Spoon the batter evenly into the prepared muffin cups, filling each about three-quarters full.
06 - Bake for 18 to 20 minutes or until a toothpick inserted into the center comes out clean.
07 - Let muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.