In a medium bowl, combine flour, oats, pecans, brown sugar, granulated sugar, cinnamon, and salt. Add melted butter and mix until resembling wet sand.

In a large bowl, whisk together sugar, lemon juice, cornstarch, vanilla extract, and spices. Add sliced pears and toss to coat.

Grease an 8x8 inch pan. Pour the pear mixture, spread evenly, then sprinkle the topping over the pears.

Preheat oven to 425°F (220°C). Bake for about 30 minutes, until fruit bubbles and topping is golden brown. Rotate halfway.

Remove from oven and cool for 15 minutes before serving.