4 pints fresh blueberries (about 8 cups)
Whipped cream or vanilla ice cream for serving
Preheat oven to 350 degrees Fahrenheit. Melt butter in small bowl in the microwave and set aside.
Combine 2 1/2 cups of blueberries and 3/4 cup of granulated sugar in a medium saucepan. Cook over low heat until the berries soften and release their juices, stirring frequently so they don't stick. This will take about 8 minutes and will be marked by the subtle hissing and bubbling of the berries. Mix in the remaining blueberries and turn into a 13 x 9 x 2-inch glass baking dish.
In another bowl, mix together the flour, walnuts, brown sugar, cinnamon, salt and remaining 6 tablespoons of granulated sugar. Slowly add in the cooled, melted butter, mixing everything together with a fork until moist clumps form. Sprinkle this crumble topping over the blueberries.
Bake the dish until the topping is golden and bubbling, about 45 minutes. Allow to cool so the juices thicken a bit and serve with whipped cream or vanilla ice cream.
PS- This is another recipe that could easily be made in ramekins for individual servings.