In a large mixing bowl, combine flour, sugar, and salt. Cut in butter using a pastry cutter or fork until mixture resembles coarse crumbs.

Add eggs one at a time, mixing well after each addition. Gradually add milk until dough comes together. Knead briefly until smooth.

Cover dough with plastic wrap and refrigerate for 20 minutes.

Meanwhile, prepare filling: In a saucepan over medium heat, combine evaporated milk, sweetened condensed milk, and heavy cream. Stir in cornstarch mixture.

Cook, stirring constantly, until mixture thickens to a pudding-like consistency, about 8-10 minutes. Remove from heat and stir in vanilla extract. Let cool completely.

On a floured surface, roll out dough to 1/8-inch thickness. Cut circles using a 4-inch round cutter.

Place 2 tablespoons of filling in center of each circle. Fold dough over to create half-moon shape, pressing edges firmly to seal. Crimp edges with fork.

Heat vegetable oil in a deep skillet to 350°F. Fry empanadas in batches, 2-3 minutes per side, until golden brown.

Remove with slotted spoon and drain on paper towels. Let cool slightly before dusting with cinnamon sugar if desired.

Serve warm or at room temperature.