1 red or pink grapefruit
2 teaspoons coconut sugar
¼ teaspoon ground cinnamon or cardamom
2 teaspoons melted butter
2 tablespoons yoghurt
Position oven rack about 3 inches from the heat source; preheat broiler. Line a rimmed baking sheet with foil.
Cut 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 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.
Broil the grapefruit, watching carefully and rotating the pan front to back once halfway through, until the tops are bubbling and golden brown, 7 to 12 minutes.
Serve grapefruit with a dollop of yoghurt in the middle