Heat oven to 350 degrees. Grease an 8-inch square baking pan (not necessary with nonstick pan).
Combine butter, 1 cup flour and the granulated sugar in a food processor. Pulse until ingredients are pebbly and crumbly; mixture will be quite dry. Press into pan, and bake for 15 minutes or until shell is evenly cooked.
If fruit is very dry, stew it in water to cover in a small saucepan until soft, 5 to 10 minutes. Drain very well, then chop. Combine in a bowl with eggs, brown sugar, remaining flour and salt.
Remove pan from oven, and pour fruit batter over crust. Bake until lightly browned and firm on edges but still a little soft in middle, about 30 minutes.
Cool, then cut into squares and serve. Store, covered and refrigerated, for up to 2 days.