Preheat your oven to 350°F (175°C) and grease a loaf pan.

In a bowl, whisk together flour, baking powder, and poppy seeds.

In another bowl, cream softened butter and sugar until light and fluffy, then mix in lemon zest.

Add eggs one at a time, mixing well after each addition; stir in lemon juice and vanilla extract.

Gradually fold in the dry mixture until just combined—avoid overmixing.

Pour the batter into the prepared loaf pan and bake for 50-60 minutes or until a toothpick comes out clean. Let cool before slicing.