01 - Preheat oven to 375°F. Line a 12-cup muffin tin with paper liners or grease thoroughly.
02 - In a large bowl, whisk together flour, poppy seeds, baking powder, baking soda, and salt until well blended.
03 - Rub lemon zest into sugar with fingertips until fragrant. Whisk in eggs, yogurt, melted butter, lemon juice, and vanilla extract until smooth.
04 - Pour wet ingredients into dry ingredients. Gently fold with a spatula until just combined. Avoid overmixing to prevent tough muffins.
05 - Divide batter evenly among prepared muffin cups, filling each about three-quarters full.
06 - Bake for 16 to 18 minutes, or until a toothpick inserted into the center comes out clean.
07 - Let muffins cool in pan for 5 minutes, then transfer to a wire rack to cool completely.
08 - Whisk powdered sugar with lemon juice, adding juice gradually to achieve desired consistency. Stir in lemon zest if using.
09 - Drizzle glaze over cooled muffins. Allow glaze to set before serving.