Whisk together the dry ingredients (flour, sugar, baking powder, baking soda, salt, and nutmeg) in a large bowl until well combined and no lumps remain.

In a separate bowl, combine the buttermilk, eggs, vanilla extract, and melted butter, stirring until smooth and fully incorporated.

Pour the wet ingredients into the dry ingredients and mix gently until just combined. The dough will be slightly sticky?do not overmix to keep the beignets tender.

Heat vegetable oil in a deep, heavy-bottomed pot to 350?F. Use a candy thermometer to maintain this temperature.

Turn the dough onto a well-floured surface and roll it out to about ?-inch thickness. Cut into 2-inch squares using a sharp knife or pizza cutter.

Carefully lower 3-4 squares into the hot oil, being careful not to overcrowd the pot. Fry for about 2-3 minutes, flipping halfway through, until puffed and golden brown on both sides.

Remove the beignets with a slotted spoon and transfer to a paper towel-lined plate to drain excess oil for about 30 seconds. While still hot, dust generously with powdered sugar.

Serve immediately while still warm.