Whisk the flour, sugar, baking powder, baking soda, and salt in a large bowl.
Whisk the buttermilk, egg yolks, and melted butter in a second bowl. Add to the dry ingredients and stir just until combined.
Beat the egg whites to soft peaks, then gently fold them into the batter.
Cook the puffs:
Heat an æbleskiver pan over medium heat and brush each well with butter. Fill each well about three-quarters full.
When the edges are set, use two skewers to turn each puff a quarter turn. Continue turning every 30 seconds until round, golden, and cooked through, about 4 to 5 minutes total per batch.
Serve:
Transfer to a plate, dust with powdered sugar, and serve warm with raspberry jam.
Notes
Do not overmix the batter or the puffs will be dense.
Keep the pan at medium heat so the centers cook before the outside browns too much.