Preheat the oven to 375.
Lightly butter an 8" square baking dish.
In a large bowl combine the 1/2 cup brown sugar and the 1/4 cup of the flour and mix well to eliminate clumps.
Add fruit to the mixture and toss until evenly coated.
Transfer the mixture to the prepared baking dish.
Stir together the oats, the remaining brown sugar and the remaining flour.
Using a pastry tool or 2 forks, blend the butter into the oat mixture until it is well combined.
Spread topping over fruit.
Bake until the top is golden brown and the fruit is bubbly (40 minutes).
Let cool 10-15 minutes and serve warm.