To make the maple bacon butter, combine all ingredients into a bowl a mix until well-combined.  Turn out onto wax paper, roll into a tight cylinder and twist the ends shut.   Chill until ready to use.  It will keep for 4-5 days in the fridge, or 3 months in the freezer.

To make the pancakes, combine the flour, sugar, baking powder and salt in a large mixing bowl.  In a second bowl, combine the yolks, the two milks, and  the melted butter. Whip the egg whites in a third bowl, until stiff peaks form.

Combine the wet and dry ingredients, and mix until smooth. Gently fold in the beaten egg whites with a rubber spatula, followed by the blueberries.

Preheat a large cast iron pan to medium/medium low and add some butter to the pan. Add batter a ladle full at a time, flipping when bubbles begin to rise to the top of the pancake and the bottom side is browned, 2 to 3 minutes on each side.

Serve immediately, with the maple bacon butter on top, and extra maple syrup for serving.