Preheat oven to 350° and place oven rack in middle position. Grease either an 8X8 or 8-9 inch pie pan with butter and set aside.
Peel pears and remove core. Dice into small chunks. Toss with melted butter, granulated sugar, and cinnamon to combine and fully coat the pears. Pour into prepared baking dish and set aside.
Hazelnut crisp
In a mixing bowl whisk together brown sugar, all purpose flour, old fashioned oats, chopped hazelnuts and cinnamon. Slice butter into tablespoon sized pieces. Add the butter to the mixture. Use your fingers to press the butter into smaller, pea sized, pieces and combine with the dry ingredients. When ready you should be able to pinch together the mixture and it hold its shape. Using your hands pinch and crumble together the topping and sprinkle over the pears.
Wrap the pear crisp in foil. Bake in preheated oven for 30 minutes. After 30 minutes remove the foil and return to the oven for 10 more minutes. The mixture will be bubbling and the hazelnut crisp be slightly golden brown. Allow it to cool slightly on a wire rack. Best served warm, with vanilla ice cream.
Notes
Store in an airtight container for 2-3 days in the refrigerator. You can reheat in either the oven or the microwave, or eat cold.