Instructions

1. In a large bowl, combine the flour and 1/2 cup of the granulated sugar. Add the softened butter and use your fingers to rub it into the flour until the mixture resembles coarse crumbs.
2. In a small bowl, whisk together one of the eggs and the vanilla extract. Add this mixture to the flour mixture and stir until a dough forms. Wrap the dough in plastic wrap and refrigerate for at least 30 minutes.
3. While the dough is chilling, prepare the custard. In a saucepan, combine the whole milk, the remaining 1/2 cup of granulated sugar, cocoa powder (if making chocolate custard), and cornstarch. Cook over medium heat, stirring constantly, until the mixture thickens and comes to a gentle boil. Remove from heat and let cool to room temperature.
4. Preheat your oven to 350°F (175°C) and grease a 12-cup muffin tin.
5. On a lightly floured surface, roll out the chilled dough to a 1/4-inch thickness. Cut out 12 circles with a cookie cutter or glass that is slightly larger than the muffin cups. Carefully press the dough circles into the muffin cups.
6. Fill each dough cup with the cooled custard, ensuring not to overfill. Beat the remaining egg and brush it over the edges of the dough for a beautiful golden finish.
7. Bake for 20 minutes, or until the edges of the pusties are golden brown. Let them cool in the tin for 10 minutes, then transfer to a wire rack to cool completely.