Heat about 2-3 inches of vegetable oil in a deep pot over medium-high heat until it reaches 365°F.

In a large mixing bowl, whisk together 2 cups of all-purpose flour, ¾ cup of granulated sugar, 1 tablespoon of baking powder, and ½ teaspoon of salt.

In a separate bowl, combine ¾ cup of buttermilk, 1 teaspoon of pure vanilla extract, and ¼ cup of melted butter.

Gently pour the wet mixture into the bowl of dry ingredients and combine until just incorporated.

On a floured surface, turn out your donut dough and roll it out to about ½ inch thick.

Carefully place three donuts at a time into the hot oil and fry for about 2 minutes on each side.

Once golden, remove the donuts from the oil and drain them on paper towels.

While still warm, roll the donuts in granulated sugar or a mix of sugar and cinnamon.