Preheat the oven to 375 ° F. Grease a 9 x 9 baking dish with butter or oil. (You can also use a cast iron skillet.)
Place the apples and pears in a large bowl.
Whisk together the flour, sugar, and cinnamon in a medium bowl.
Toss the flour mixture with the fruit and lemon juice.
Arrange in the prepared baking dish.
In a medium bowl, combine the brown sugar, butter, rolled oats, chopped pecans, and salt.
Use clean fingers to work the butter into the dry ingredients until the mixture resembles a coarse meal.
Spoon the mixture over the fruit.
Bake for 1 hour, until browned and bubbly.
Let cool for 10 minutes before serving.
Serve with whipped cream or ice cream, if desired. Enjoy!