Preheat your oven to 350°F (175°C). Gather your ingredients and equipment.

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

Add eggs one at a time, mixing well after each addition. Mix in the vanilla extract.

In a separate bowl, whisk the flour, baking soda, and salt together, then gradually add to the wet ingredients.

Fold in the lemon juice and poppy seeds until just combined.

Pour the batter into a prepared cake pan and bake for 30 minutes or until a toothpick comes out clean.

Allow the cake to cool in the pan for 10 minutes before transferring to a wire rack to cool completely.