Preheat oven to 350F. Grease a 9″ x 13″ pan (glass) and set aside.

Rinse blueberries if using fresh. Place fresh or frozen blueberries into a pot along with white sugar, lemon zest, and water. Stir to coat and allow to sit for 15-20 mins.

Meanwhile, in large mixing bowl, combine all purpose flour, brown sugar, and melted butter. Mix well until thoroughly combined. Set aside.

Place pot of blueberries on the stove, and cook on medium heat for 15 mins. Stir frequently, occasionally mashing blueberries with a fork (careful – it’s hot!).

Into the blueberries, stir cinnamon, nutmeg and vanilla flavor, and gently cook 5 more minutes. Blueberries with thicken slightly.

Remove blueberries from heat and carefully pour into the greased pan. Top with the flour mixture.

Bake in preheated oven until bubbly, and the flour mixture has browned (approximately 20 minutes).

Remove from oven and cool before enjoying.