Gather all ingredients. Preheat the oven to 375 degrees F (190 degrees C). Grease a 2-quart casserole dish or 9-inch square baking dish.

Stir oats, brown sugar, 1/2 cup flour, 1 teaspoon crystallized ginger, and cinnamon together in a medium bowl; rub in butter until mixture is crumbly with pea sized lumps. Set aside.

Stir white sugar, 2 tablespoons flour, and 2 teaspoons of crystallized ginger together in a separate bowl. Add sliced pears and toss to blend.

Transfer pear mixture into prepared baking dish; sprinkle with crisp topping mixture.

Bake in the preheated oven until pears are soft and topping is golden brown, about 30 to 35 minutes.

Cool slightly before serving with vanilla ice cream.