For filling, combine sugar and cornstarch in a small bowl. Add berries and toss to coat evenly.
For topping and bottom layer, combine oats, brown sugar, flour, cinammon, sugar, ginger, and salt in a bowl. Cut in cold butter using two knives -- then mix with fork until mixture resembles coarse crumbs.
Pat half of the oat mixture on bottom of a 2-quart glass pan. Top with berry concoction. Finish off by crumbling the remainder of the oats on top of the berries.
Bake 20-25 minutes until oats are golden brown and berries are bubbling around edges.