Combine flour, baking powder, and salt in a large bowl. Combine milk, eggs, and shortening; add to dry ingredients, stirring just until moistened.
Shape dough into 1 1/2-inch balls, and place on a lightly floured surface. Roll each ball into a very thin circle about 6 to 7 inches in diameter.
Heat 1 inch of oil in a large, heavy skillet to 375°. Fry each buñuelo 1 minute on each side or until lightly browned. Drain on paper towels.
Combine sugar and cinnamon; sprinkle over buñuelos.