Preheat the oven to 350 degrees.
In a large mixing bowl, combine the berries, Grand Marnier, granulated sugar, and two tablespoons of the flour. Toss to mix and let sit for 15 minutes.
Grease four 8-ounce ramekins with one teaspoon of the butter. Divide the berry mixture equally among the ramekins.
In a small mixing bowl, cream the remaining stick of butter with the brown sugar until smooth. Add the cinnamon, the remaining 1/2 cup flour, and the oats. Mix well.
Spread the oat mixture evenly over the berries. Put the ramekins on a baking sheet and bake until lightly golden, about 30 minutes. Remove from the oven and let cool slightly. Top each cobbler with a scoop of ice cream, if you wish, to serve.
Makes 4 servings