In a small bowl, stir together the maple butter, pecans and a pinch of salt.
Set the filling aside.
In a bowl, whisk together the flour, baking soda, baking powder, granulated sugar, 1 1/2 tbs of the cinnamon, the nutmeg, allspice and the 3/4 tbs salt.
In another bowl, whisk together the egg yolks, buttermilk and sour cream.
Whisk the egg yolk mixture into the flour mixture until well combined; the batter will be lumpy.
Using a rubber spatula, gently stir the egg whites into the batter in two additions.
Heat a filled-pancake pan over medium heat.
Put 1/2 tbs butter in each well, add 1 tbsp batter and cook for 2 minutes.
Spoon 1 tbs maple filling into the center of each pancake and top with 1 tbsp batter.
Cook until the bottoms are golden brown and crispy, about 2 minutes.
Using 2 skewers, flip the pancakes over and cook until golden and crispy, about 3 minutes more.
Transfer the pancakes to a plate.
Repeat with the remaining batter.
In a small bowl, stir together the confectioners sugar and the remaining 1/4 tbs cinnamon and sprinkle on the pancakes.
Ready in 35 min.