Preheat your oven to 350°F (175°C) and grease a 9-inch round cake pan.

In a bowl, whisk together flour, baking powder, baking soda, and salt. Set aside.

In a separate bowl, cream the softened butter and granulated sugar until light and fluffy.

Beat in the eggs one at a time, then mix in the lemon zest and lemon juice until well combined.

Gradually add the dry mixture to the wet mixture, alternating with buttermilk, beginning and ending with the dry ingredients. Stir in poppy seeds.

Pour the batter into the prepared cake pan and smooth the top.

Bake for approximately 25-30 minutes, or until a toothpick inserted into the center comes out clean.

Let the cake cool in the pan for 10 minutes, then transfer it to a wire rack to cool completely before slicing and serving.