Place 3 cups of blueberries in a medium sized saucepan. Sprinkle the sugar, cinnamon, and nutmeg on the top of the berries. Mix the water and cornstarch in a bowl and pour it into the pan with the sugar, spices and berries. Cook over medium low heat until it starts to thicken. Gently stir as the mixture thickens but, don’t smash the berries. Add the butter and lemon juice and continue to cook until it reaches a pie consistency.