Creating Grapefruit Poppy Seed Cake is straightforward with these easy steps:

1. Preheat Oven: Begin by preheating your oven to 350°F (175°C). Grease and flour an 8-inch round cake pan.
2. Mix Dry Ingredients: In a medium bowl, whisk together the flour, baking powder, baking soda, salt, and poppy seeds.
3. Cream Butter and Sugar: In a large bowl, cream the softened butter and granulated sugar until light and fluffy.
4. Add Eggs: Beat in the eggs, one at a time, ensuring each is well incorporated before adding the next.
5. Incorporate Wet Ingredients: Add the grapefruit juice, zest, and vanilla extract to the egg mixture. Mix until well combined.
6. Combine Dry and Wet Mixtures: Gradually add the dry ingredients to the wet mixture, stirring until just combined.
7. Pour Batter into Pan: Pour the batter into the prepared cake pan, smoothing the top with a spatula.
8. Bake: Place the pan in the preheated oven and bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean.
9. Cool the Cake: Remove from the oven and allow to cool in the pan for about 20 minutes before transferring to a wire rack to cool completely.
10. Frost (Optional): 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.

These steps guide you through making this delightful and refreshing cake. Each phase builds anticipation for the refreshing experience to come!