Heat your oven to 170 degrees F, sometimes called the "keep warm" setting.
Get out 3 mixing bowls: large, medium, and small.
Add the butter to the large bowl and microwave until it is melted. Set aside to cool a little bit.
In the medium bowl, whisk together flour, sugar, salt, baking soda, and baking powder.
Add the buttermilk and milk to the melted butter.
Separate the eggs: add the whites to the small bowl and the yolks to the wet ingredients in the large bowl. Whisk in the yolks.
Use a small whisk or fork to beat the egg whites a little bit, just 20 seconds or so until they start getting a little bubbly. It will help them fold in evenly.
Add the buttermilk mixture to the dry ingredients and stir roughly with a wooden spoon. Don't overdo it! Just barely combine it. There should still be streaks for flour.
Beat the egg whites a little then add them to the batter. Fold in gently. It's okay if there are still streaks of egg white.
Heat a griddle or large frying pan over medium heat.
When it is hot, smear a little bacon grease over the griddle. Or if you cooked bacon before, leave the bacon grease in the pan!
Scoop the batter using a half cup measurement.
When bubbles on top start to pop, flip the pancakes. They should be a nice golden brown and crispy on the edges!
Continue cooking for another 2-3 minutes until they are golden and crispy on both sides.
Remove the pancakes to a cooking rack and keep warm in the oven that you turned on.
Serve with lots of butter and syrup!