In a mixing bowl, combine 2 cups of all-purpose flour, 2 tablespoons of sugar, and 1 large egg. Mix until a dough forms, then knead it on a floured surface for about 5 minutes until smooth and elastic. Wrap the dough in plastic wrap and let it rest for at least 30 minutes.

After resting, lightly flour your work surface and roll out the dough to a thickness of about 1/8 inch. Use a 3-inch round cookie cutter to cut out circles.

In a deep saucepan, heat oil to 350°F (175°C). Carefully drop the dough circles into the hot oil, frying them in batches for 1-2 minutes on each side until golden brown. Remove the shells using a slotted spoon and drain them on paper towels.

In a mixing bowl, combine 1 cup of ricotta cheese, 1/2 cup of powdered sugar, and 1 teaspoon of vanilla extract. Mix until smooth and creamy, incorporating any optional citrus zest.

Once the pastry shells have cooled completely, take a piping bag and fill it with the ricotta mixture. Carefully pipe the filling into each shell.

Before serving, sprinkle with chocolate chips or crushed pistachios for garnish. Serve immediately for the best texture.