In a medium bowl combine brown sugar, oatmeal, flour and cinnamon. Cut in the butter until only small pieces remain. Set aside.
For the filling:
Peel and slice the apples and pears into 1/4 inch slices. Toss gently with lemon juice to prevent browning.
In a medium bowl, combine the remaining flour, cinnamon, nutmeg, brown sugar and vanilla. Add to the sliced apples and pears, tossing gently to coat. Add the topping evenly over the fruit mixture.
Transfer to a buttered 8×8 inch square baking dish. Bake for 45 minutes or until the fruit is tender and the topping is crisp.
Notes
For the filling, I substituted 2 tsp. apple pie spice from Penzeys in place of the cinnamon and nutmeg. I like the touch of clove spices the apple pie spices add. Additionally, the original recipe only called for 2 Tbsp. flour to be added to the filling. I added three instead, as our pears and apples were particularly juicy. I switched the recipe to use equal amounts of sliced pears and apples.Adapted from Baked By Rachel.