Preheat the oven to 375 degrees Fahrenheit and lightly butter an 8" square baking dish.

In a large bowl, combine 1/2 cup brown sugar and 1/4 cup of the flour. Mix well to eliminate any clumps.

Add the fruit and toss until evenly coated.

Transfer mixture 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 the topping over the fruit.

Bake until the top is golden brown and the fruit is bubbly (about 40 minutes).

Let cool 10-15 minutes and serve warm.