Mix flour, salt, and instant yeast together in a small bowl.Heat the milk in microwave until boiling hot.Combine butter and sugar in a mixing bowl and pour the steaming milk over the top. Stir so that the butter melts and the sugar dissolves. Allow to cool to a lukewarm temp.Add the egg and vanilla to the milk mixture and mix thoroughly.Add the wet ingredients to the dry ingredients and mix until a dough is formed. Knead dough for 3-5 minutes.Place dough into a lightly oiled bowl. Cover and allow it to rise for about 1 hour or until it has doubled in size.Roll out dough to about 1/4 inch thick on a floured surface and cut into squares.Set dough pieces aside for 30 minutes or until they have almost doubled in size.Set airfryer at 390 degrees and cook dough squares for 6 minutes, flipping them over halfway through.Cover with powdered sugar and enjoy!