Bring maple syrup and 3/4 cup cranberries to a boil over medium-high heat. Reduce heat to low, and simmer 3 minutes or until cranberries pop. Crush cranberries in saucepan using a spatula. Stir in remaining 1/4 cup cranberries; simmer just until they begin to pop (about 2 minutes). Add butter, and stir until melted.