Frozen blueberries can be exchanged for fresh berries. No need to defrost them!
To keep your blueberries from sinking, toss them in some flour before you add them to the batter. This little trick will do the job.
A couple teaspoons of lemon zest mixed in with the wet batter brings out the combined flavors!
An alternative topping: use a simple lemon glaze made from powdered sugar that is tasty on many baked goods. Whisk together 1 tbsp of lemon juice with 1 tbsp milk and a cup of powdered sugar. Let the bread cool about 10 minutes before drizzling on top. Then allow the glaze to harden, about 20 minutes before slicing into it.
Feel free to replace whole wheat flour for all-purpose flour for a gluten free treat.