Preheat oven to 400°

In a medium mixing bowl, whisk together flour and brown sugar.

Add 1 cup of butter and mix on low speed until crumbly.

In a medium bowl, whisk sugar, salt, nutmeg and cinnamon together and set aside.

Rinse blueberries and add to another medium bowl. Add lemon juice. Toss to coat. Stir in walnuts.

Mix in sugar mixture and stir until blueberries and walnuts are coated well.

Pour fruit mixture into a 9 x 13 inch baking dish.

Add the remaining ¼ cup butter (sliced) and just place on top of the fruit mixture randomly.

Add the flour mixture on top of fruit and spread evenly.

Bake uncovered at 400° for 40 minutes until golden brown.

Serve warm with ice cream or whipped cream.