Simple, rustic and such an easy cake for a weekend breakfast. Leftovers are delicious warmed in a microwave and served with vanilla ice cream. Fresh or frozen blueberries can be used; however I prefer to use unsweetened frozen blueberries for this recipe as their flavor is consistently good; the berries are picked at their peak and then quickly frozen to ensure high quality fruit. If using fresh berries, sort through the berries and remove any that are soft or moldy, and remove all stems.