You can double this easy apple crisp recipe for a 13" x 9" pan. It's from The Moosewood Cookbook, by Mollie Katzen
Preheat oven to 375 degrees. Grease a 9” x 9” square pan.
Peel and core 3-5 apples (I use a mix of Empire, Granny Smith, and MacIntosh). Slice or cube and put into pan (leave a little room for topping).
Sprinkle apples with 2-3 T. lemon juice and ¼ c. white sugar.
Make topping:
1 c. flour
1 c. rolled oats
2-3 T. brown sugar
½ t. cinnamon
Dash of nutmeg and of allspice (or a little more)
¼ t. salt
5 T. melted butter or olive oil
Mix topping well and sprinkle over apples. Pat firmly into place.
Bake for 35-40 min. until brown and fruit is bubbling around the edges. Serve hot, warm, or at room temperature, plain or a la mode.