Preheat oven to 360 degrees F. In a mixing bowl, combine blueberries and vanilla. Toss to combine, set it aside.
Combine brown sugar, cinnamon, nutmeg and oatmeal in a bowl. Cut in the butter (click for How to Cut in Butter).
Add walnuts and mix well.
Place blueberries in a baking dish and sprinkle oatmeal mixture over blueberries.
Bake for about 45-50 minutes or until topping looks crunchy and blueberries are tender. Serve cold or hot (you can serve with ice cream or whipped cream).