Melt 1 tbsp. butter in a large frying pan over medium heat. Stip in 1 ½ cups each blackberries and blueberries, ¼ cup sugar, and 1 tbsp. fresh lemon juice. Cook until juices are released from fruit, about 4 minutes. Stir in 2 tbsp. chopped fresh thyme leaves, then 1 cup raspberries. Add more sugar and lemon to taste, depending on sweetness of berries. Serve warm over ice cream. Makes 6 servings.