In a large bowl, mix the all-purpose flour, tapioca flour, yeast, baking powder, and salt. Add the whole milk and stir with a wooden spoon until smooth. Add the condensed milk and butter and stir again until the dough is smooth and very sticky. Cover the bowl tightly with plastic wrap and let proof at room temperature for 1 to 2 hours until doubled in size.

Generously dust a work surface with flour. Scrape out the dough and dust the top with more flour. Pat down the dough and use a bench scraper to fold the dough onto itself, like folding a letter. Turn the dough 90 degrees and fold again. Keep in mind that this dough is very sticky, and you will need to continuously dust with more flour. Roll out the dough to a thin sheet about ⅛ inch (0.25 centimeters) thick. Cut the sheet into square shapes (which is easier and faster), or use a pastry cutter to cut out little rounds. Gather the scraps, roll them out, and cut again until all the dough is used.

Arrange the pieces on a flour-dusted baking sheet and cover with plastic wrap. Let rise at room temperature for about 1 hour, until puffed.

In a deep, narrow pot over medium-high heat, heat 2 cups of the oil. The smaller and deeper the pot is, the less oil you’ll need. Once you stick a wooden chopstick into the oil and it starts bubbling at the edges, the oil is ready. Working with 2 to 3 pieces at a time, fry the dough. Once the dough gets heated, it will start to puff up. Flip before the first side gets browned—otherwise, it will always revert back to the same side because of the air on the inside. Keep flipping a few times until both sides are golden brown.

Remove with a slotted spoon and transfer to a wire rack. Repeat with the remaining dough.

Generously dust with powdered sugar and serve warm.