In a large mixing bowl, combine flour, baking powder, salt, and sugar.

Add butter and egg, mixing with your hands or a spoon until the dough starts to come together.

Gradually add warm water, mixing until a soft dough forms. Knead on a floured surface for about 5 minutes until smooth.

Cover the dough and let it rest for 30 minutes.

Meanwhile, mix the granulated sugar and cinnamon in a shallow bowl and set aside.

Divide the dough into 8-10 equal pieces. Roll each piece into a thin circle (as thin as a tortilla).

Heat about 1 inch of oil in a deep skillet or pan to 350°F (175°C).

Carefully place one buñuelo at a time into the hot oil and fry until golden and crisp, about 1-2 minutes per side.

Remove and drain on paper towels. Immediately coat both sides with the cinnamon-sugar mixture while still warm.

Repeat with remaining dough. Serve warm or at room temperature.