First, preheat your oven to 350 degrees Fahrenheit (175 degrees Celsius). Grease and flour a 9-inch (23cm) round cake pan.

In a medium bowl, whisk together the flour, poppy seeds, baking powder, baking soda, and salt. Set aside.

In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy.

Beat in the eggs one at a time, ensuring each egg is fully incorporated before adding the next one.

Add the lemon zest, lemon juice, buttermilk, and vanilla extract to the butter mixture. Then, mix well.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Pour the batter into the prepared cake pan and smooth the top with a spatula.

Bake in the preheated oven for 30 to 35 minutes, or until a toothpick inserted into the center of the cake comes out clean.

Remove the cake from the oven and let it cool in the pan for about 10 minutes. Then, transfer the cake to a wire rack to cool completely.

While the cake is cooling, prepare the lemon glaze by whisking together the lemon juice and powdered sugar until smooth. Set aside.

To make the lemon cream cheese frosting, beat the softened cream cheese and butter together until smooth and creamy. Gradually add the powdered sugar, lemon juice, and lemon zest, beating until well combined and fluffy.

Once the cake has cooled, place it on a serving plate. Drizzle the lemon glaze over the top of the cake, allowing it to drip down the sides.

Spread the lemon cream cheese frosting over the cooled cake, covering the top and sides.

Optionally, garnish the cake with additional lemon zest or poppy seeds for decoration.

Finally, slice and serve this delicious lemon poppy seed cake!