In a large bowl, whisk together flour, sugar, baking powder, and salt.
In a separate bowl, mix milk, eggs, and melted butter until well combined.
Gradually add the wet ingredients to the dry ingredients, stirring until a dough forms.
Transfer the dough to a lightly floured surface and knead gently for about 1 minute.
Roll out the dough to 1/4 inch thickness and cut into squares.
Heat vegetable oil in a deep fryer or large pot to 350°F (175°C).
Carefully drop the dough squares into the hot oil, a few at a time.
Fry for 2-3 minutes on each side until golden brown.
Remove beignets from the oil and drain on paper towels.
Dust generously with powdered sugar before serving.