Line a rimmed baking sheet with foil.
Cut each grapefruit in half, then trim a thin slice off the bottom so it sits level.
With a paring knife or grapefruit knife, cut around each segment; remove any seeds.
Place the grapefruit halves on the prepared baking sheet.
Combine brown sugar and cinnamon (or cardamom) in a small bowl.
Brush each grapefruit half with butter, then sprinkle with about 2 teaspoons of the sugar mixture.
Meanwhile, beat cream in a small bowl until stiff.
Beat in yogurt, granulated sugar and vanilla just until combined.
Serve each grapefruit topped with a heaping tablespoon of the vanilla cream.
- Daily Values (DVs) are the recommended amounts of nutrients to consume each day.
(-) Information is not currently available for this nutrient.
