Preheat oven to 350 degreesIn a large mixing bowl, combine apples, pears, lemon juice, vanilla, granulated sugar, cinnamon, nutmeg and flour. Gently mix until apples and pears are well coated. Let the mixture sit aside while preparing the crumble.For the crumble topping: in another large mixing bowl, combine flour, old fashion oats, brown sugar, granulated sugar, salt, cinnamon and nutmeg. Whisk together. Mix in the diced butter with your fingers until you have large crumbles.Place the apple and pear mixture into a 12 inch skillet. Sprinkle the crumble topping evenly over the apples and pears.Bake for 40 to 45 minutes, or until brown and bubbly.Serve warm or at room temperature with ice cream or whipped cream.