Preheat the oven to 375 degrees F and butter a 2-quart baking dish. Make the filling: Toss the blueberries, granulated sugar, flour, lemon juice and salt in a medium bowl. Transfer to the prepared baking dish.
Make the topping: Combine the brown sugar, flour, oats, nuts, lemon zest, cinnamon and salt in a separate bowl. Using your fingers or a pastry blender, work the butter into the flour mixture until coarse crumbs form. Scatter the topping over the blueberry mixture.
Set the dish on a baking sheet and bake until the topping is golden brown and the filling is bubbling, 45 to 50 minutes. Let cool slightly before serving.
Photograph by Kang Kim
Courtesy of Food Network Magazine