1. In a large bowl, combine the flour, 1/4 cup sugar, and 1 teaspoon salt. Sprinkle the yeast over the top.

2. In a separate bowl, whisk together the warm milk, softened butter, egg, and vanilla extract.

3. Pour the milk mixture into the flour mixture and stir until a shaggy dough forms.

4. Turn the dough out onto a lightly floured surface and knead for 5-7 minutes, until smooth and elastic.

5. Place the dough in a lightly greased bowl, cover, and let rise for 1 hour or until doubled in size.

6. Meanwhile, prepare the custard filling. In a medium saucepan, whisk together the milk, 1/2 cup sugar, egg yolks, cornstarch, and 1/4 teaspoon salt.

7. Cook the custard over medium heat, stirring constantly, until it thickens, about 5-7 minutes. Remove from heat and let cool completely.

8. Punch down the dough and roll it out into a large rectangle, about 12×18 inches.

9. Spread the cooled custard filling over the dough, leaving a 1-inch border.

10. Carefully roll the dough into a tight log, starting from the short side.

11. Slice the log into 12 equal pieces and place them in a greased 9×13-inch baking dish.

12. Cover the dish and let the rolls rise for 30 minutes.

13. Preheat the oven to 350°F.

14. Bake the rolls for 25-30 minutes, or until golden brown.

15. Serve warm and enjoy!