Preheat the oven to 375 degrees F (190 degrees C).
Cut the room temperature Unsalted Butter into small pieces.
In a large mixing bowl, combine the Unsalted Butter (5 tablespoon), Egg (2), Sour Cream (1/2 cup), and Milk (1/2 cup).
Whisk the wet ingredients until the butter just forms tiny pebbles.
In a medium mixing bowl, whisk to combine the Whole Wheat Flour (1 1/3 cup), Granulated Sugar (2/3 cup), Baking Powder (2 teaspoon), Baking Soda (1/4 teaspoon), and Salt (1/4 teaspoon).
Rinse the Fresh Blueberries (1/2 cup).
Pour the dry ingredients over the wet and mix until just combined.
Gently stir in the blueberries (1/2 cup). Be careful not to overmix the batter!
Line a muffin pan with paper liners.
Evenly distribute the batter by spooning it into the muffin tins.
Sprinkle the tops with a little bit of extra sugar.
Bake at 375 for 15-20 minutes, or until golden all over.
Serve warm from the oven, or allow to cool and store in an airtight container at room temperature for up to three days. Alternatively, you can wrap each muffin in plastic wrap and place in a ziploc bag to store in the freezer.