01 -
Preheat the oven to 375°F (190°C) and spray a 2-quart baking dish or a 9x9 inch baking dish with non-stick cooking spray. Set aside.
02 -
In a medium bowl, whisk together flour, brown sugar, granulated sugar, cinnamon, nutmeg, and salt until combined. Cut the chilled butter into the mixture until it resembles coarse crumbs. Stir in the ¼ cup of chopped walnuts.
03 -
In a large bowl, combine raspberries, ¼ cup granulated sugar, lemon juice, lemon zest, and 1 cup of chopped walnuts. Stir gently to combine and let sit for 5 minutes. Stir again, then pour into the prepared baking dish.
04 -
Sprinkle the crumb topping evenly over the raspberry mixture. Bake uncovered for 30-35 minutes, or until the topping is golden brown.
05 -
Allow the crumble to cool for 10-15 minutes before serving. Optionally, top with a scoop of vanilla ice cream.