Preheat oven to 350°F
Brown your butter. Take your two tablespoons of butter and put into a small stainless or light colored sauce pan over medium heat. Stir after butter melts. Butter will bubble then foam, and the milk solids will brown and begin to smell nutty and fragrant. When toasted, remove from heat and pour into a small bowl immediately.
Thoroughly grease donut pan (if not non-stick) with either butter or cooking spray
In a medium bowl, mix together, flour, salt, granulated sugar, baking powder and baking soda.
In another medium bowl, whisk together egg plus additional yolk, buttermilk, browned butter, oil, and vanilla paste.
Pour wet ingredients into dry and mix with a spatula or spoon until just combined.
Transfer batter into a piping bag or spoon batter into donut pans. Cavities should be about 2/3 full.
Bake donuts for about 12 minutes. You can test one with a toothpick to make sure it comes out clean.
While donuts bake, fill a large ziplock bag with your powdered sugar.
Let donuts cool in pan for about 5 minutes. Remove from donut pan and put into bag of powdered sugar while warm. Toss in the sugar. Place on a wire cooling rack to allow cooling.
When donuts are cool, put them back into the powdered sugar for a second coating of sugar.
Keep donuts in a paper bag, pastry cardboard box or uncovered container for up to 1 day. Enjoy!
