Combine the oats, brown sugar, cinnamon, baking powder and salt in a bowl. Add the egg, milk and oil and stir until combined. Fold in the diced pear and cranberries, then pour into a greased 9×9 inch casserole dish. Meanwhile, melt the butter over low heat in a small skillet. Add the sugar and continue cooking over low heat, stirring frequently, until smooth, about 5 minutes. Add the walnuts and cook an additional minute. Remove from heat and stir in the maple syrup. Pour the walnut mixture on top of the oatmeal in the casserole dish and back at 350 degrees for 20-25 minutes, until set and lightly golden brown around the edges. Serve warm, with a splash of milk, if desired. Enjoy!