1. In a large bowl, combine the softened butter and flour

2. Mix until the dough looks like coarse crumbs

3. Slowly add the cold water and mix until a smooth dough comes together

4. Wrap the dough and refrigerate for 30 minutes

5. Preheat the oven to 375°F/190°C

6. On a lightly floured surface, roll out the dough to about 3 mm thick

7. In another bowl, whisk together the heavy cream, eggs, salt, and white pepper

8. Spread this cream mixture evenly over the dough, leaving a 2.5 cm border around the edges

9. Sprinkle the grated aged cheddar cheese and chopped fresh dill over the top

10. Fold the edges of the dough inward to create a rustic pastry square

11. Place the pastry on a baking sheet lined with parchment paper

12. Bake for 35 to 40 minutes, or until golden brown

13. Take it out of the oven and let it rest for 10 minutes

14. Slice and serve warm, being careful of the hot filling