In a medium mixing bowl, combine the cornstarch, yuca flour, finely grated feta, queso fresco, baking powder, sugar, salt, egg, and milk. Mix thoroughly with your hands, kneading until a soft and smooth dough forms. If the dough feels too dry, add a touch more milk, a tablespoon at a time, to reach the right consistency.

Once the dough is ready, pinch off small portions and roll them between your palms to form uniform balls about the size of a walnut.

Pour canola or vegetable oil into a deep, heavy-bottomed pot, filling it to a safe level for deep-frying. Heat the oil slowly until it reaches 300°F (150°C); the oil should be warm but not overly hot to ensure even cooking.

Carefully drop the dough balls into the oil in small batches. Fry for 3 to 4 minutes, gently turning them to ensure they cook evenly on all sides, until the buñuelos are golden brown and puffed.

Using a slotted spoon, remove the buñuelos from the oil and drain them on a plate lined with paper towels to absorb excess oil.

Serve the buñuelos warm, fresh from the fryer, for the best texture—crispy on the outside with a tender, cheesy center.