In a saucepan, heat brown sugar and butter, stirring constantly, until bubbly. Add peaches; stir gently until peaches are barely tender, about 5 minutes. In a cup, combine rum and cornstarch; stir mixture into peaches. Cook and stir until clear and thickened, about 2 minutes. To serve: Split biscuits and plate bottoms. Spoon half of the peach mixture over the bottoms. Replace the biscuit tops; cover with the remaining peach filling. Garnish with blueberries and mint leaves. |