Preheat the oven to 375.
Lightly butter an 8" square baking dish.
In a large bowl combine 1/2 cup brown sugar and 1/4 cup of the flour and mix well to eliminate clumps.
Add fruit and toss until evenly coated.
Transfer to the prepared baking dish.
Stir together oats, remaining brown sugar and remaining flour.
Using a pastry tool or 2 forks, blend butter into oat mixture until 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.