Old-Fashioned Apple Crisp (Alison Pantry)

6 medium (6 cups) apples, peeled, cored, sliced
3/4 cup firmly packed brown sugar
3/4 cup old fashioned regular cookie oats
½ cup all-purpose flour
1 tsp cinnamon
½ cup cold butter
Vanilla ice cream

Preheat oven to 375. Place apples in ungreased 8-inch square baking dish. Combine brown sugar, oats, flour and cinnamon in medium bowl; cut in butter until mixture looks like coarse crumbs. Sprinkle sugar mixture over apples. Bake 25-35 minutes, or until apples are tender and topping is golden brown. Serve warm, with ice cream.