Heat a large pot of neutral cooking oil (such as vegetable or canola) over medium heat until it registers 350ºF.

While the oil is heating, stir together the eggs, 1/2 cup sugar and ricotta cheese until mostly smooth. Add in the flour and vanilla and stir just until combined.

In another bowl, combine the remaining 1/2 cup sugar and cinnamon.

Using a small ice cream scoop, drop the batter into the hot oil, about 1 tablespoon of batter each. Fry until golden brown and cooked though. Transfer to a paper towel lined plate for a few minutes, then transfer to the bowl with the cinnamon sugar. Toss the doughnuts in the cinnamon-sugar mixture to coat. Continue to cook the doughnuts in batches until all of the batter has been used.