Prepare the oil for frying. In a dutch oven or large pot, heat 3-4 inches of oil over medium-high heat. Heat to 350°F-360℉ then turn the heat down to medium so it doesn't get too hot.
Mix the cinnamon and sugar for the coating in a wide bowl or plate for rolling after the bolinhos are cooked and hot.
Mix Dry ingredients. To a medium bowl, mix together the flour, baking powder, and salt.
In a large bowl, whisk the eggs, sugar, and vanilla. Next whisk in the milk.
Using a mixing spoon to combine, add the flour mixture to the wet ingredients. Stirring constantly until blended smooth into a thick batter.
Check the temperature of your oil. If you do not have an oil thermometer, you can test the oil with a small amount of your dough. It should bubble as soon as it hits the oil but there should be no smoke.
When the oil is ready (350°F-360℉), form your bolinhos de chuva using two regular soup spoons. Scoop a good amount onto one and then push this out into the oil using the other spoon.
Add the bolinhos in batches, 5-6 at a time - do not crowd the pot. Gently flip the bolinhos over to ensure they are golden brown on all sides. They are done when completely golden brown (maybe 3-4 minutes). Remove them with a slotted spoon or spatula and place on a pan lined with paper towel. If the oil temp drops below 350℉, turn up heat to get back to temp before adding more bolinhos.
While the bolinhos are still hot, but no longer dripping with oil, roll them in the cinnamon sugar mixture. Transfer to a separate plate and serve immediately. Enjoy!