Preheat oven to 350 degrees F.
Spray two loaf pans with non stick cooking spray. I prefer to line mine with foil first.
In a mixer, combine butter, Greek yogurt and sugar until light and fluffy, approximately 2-3 minutes. Add in eggs, one at a time, mixing on low after each egg. Add in lemon zest and stir to combine.
In a separate bowl, combine flour, baking powder, baking soda and salt.
Add half of the dry mixture to the butter and sugar mixture, and stir until just combined. Add lemon juice, vanilla, lemon extract (if using) and 1/2 of the buttermilk to the mixture and stir until just combined. Add the remaining dry mixture, stirring until just combined, followed by the remaining buttermilk, stirring until just combined. Gently fold in the blueberries until just combined.
Divide the batter between both loaf pans. Place in the oven and bake for 45 minutes to one hour or until a toothpick inserted into the center comes out clean. Remove from oven and allow to cool.
If desired you can make a glaze of 3 cups powdered sugar and 3-5 tablespoons lemon juice to drizzle over the top of your loaves. Just mix the two together in a bowl until you get the consistency that you want. More liquid to make it thinner, more powdered sugar to make it thicker. I like to add a few drops of vanilla and a sprinkle of salt to give the flavor a bit more depth. It works best to pour the glaze on while the bread is still warm, but out of the pan (otherwise you can end up with your bread a bit stuck in the pan).
Enjoy! I prefer to store my bread covered, in the fridge.