1) Remove the ends of the grapefruits to stabilize on the cutting board. Using a sharp knife, remove the skin and bitter pith from the flesh. Over a small bowl, hold grapefruit in 1 hand and carefully remove the segments by sliding the knife between the flesh and the membrane. Toss grapefruit pieces with brown sugar and vanilla and divide among 6 ramekins.
2) In a large bowl, beat egg whites until light and fluffy. Add sugar and beat until meringue is glossy and holds stiff peaks. Top each ramekin with 60ml of ice cream. Cover with meringue and bake until golden brown, about 7 minutes.