01 -
Preheat your oven to 350°F (175°C). Grease and flour an 8-inch round cake pan.
02 -
In a medium bowl, whisk together the flour, baking powder, baking soda, salt, and poppy seeds.
03 -
In a large bowl, cream the softened butter and granulated sugar until light and fluffy.
04 -
Beat in the eggs, one at a time, ensuring each is well incorporated before adding the next.
05 -
Add the grapefruit juice, zest, and vanilla extract to the egg mixture. Mix until well combined.
06 -
Gradually add the dry ingredients to the wet mixture, stirring until just combined.
07 -
Pour the batter into the prepared cake pan, smoothing the top with a spatula.
08 -
Place the pan in the preheated oven and bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean.
09 -
Remove the pan from the oven and allow the cake to cool in the pan for about 20 minutes before transferring to a wire rack to cool completely.
10 -
Once cooled, you may choose to frost the cake with a light glaze made from powdered sugar and grapefruit juice, or enjoy it as is for a lighter treat.