For the cake:
2 cups grapefruit-flavored sparkling water
1/2 teaspoon agar-agar powder
3/4 teaspoon creamed honey
For the syrup:
1/2 cup red grapefruit juice
1/2 cup water
3 tablespoons creamed honey
Pinch of beet powder
Segmented pink grapefruit
Blanched almond flour
Place a half sphere silicone mold onto a baking sheet and set aside.
In a medium pot, whisk together the sparkling grapefruit water, agar-agar, and creamed honey. Whisk on medium heat until the agar-agar and honey have dissolved, about 5 minutes.
Pour the mixture into a glass measuring cup and allow the mixture to cool for 10 minutes. Once the mixture has cooled, slowly pour the liquid into the molds. Place the tray into the refrigerator for 2 hours until set.
While the raindrop cake sets, make the grapefruit syrup. Place all of the syrup ingredients into a small pot and cook on medium heat until the liquid has reduced by more than half, about 20 minutes. Pour the reduced syrup into a small glass measuring cup and allow it to chill in the fridge until ready to use.
To assemble the cake, remove from the mold, place on top of segmented grapefruit, drizzle with syrup, and sprinkle with almond flour. So refreshing!