1. 1. Preheat your oven to 200°C (400°F).

2. 2. In a large mixing bowl, combine the flour, cold butter, and cold water. Mix until a smooth dough forms. Add the chili flakes and mix well.

3. 3. On a lightly floured surface, roll out half the dough to a thickness of about 3 mm (1/8 inch). Transfer the dough to a 23 cm (9-inch) pie dish and trim the edges to fit.

4. 4. In a large skillet, heat the olive oil over medium heat. Add the diced chicken, onion, and garlic. Cook until the chicken is browned and the onion is translucent, about 5-7 minutes.

5. 5. Stir in the heavy cream, and season with salt and pepper. Simmer for 2-3 minutes, then remove from heat and let cool slightly.

6. 6. Pour the chicken mixture into the pie crust. Top with the padron peppers and fresh basil leaves.

7. 7. Roll out the remaining dough to a thickness of about 3 mm (1/8 inch) and use it to cover the pie. Crimp the edges to seal the pie and cut a few slits in the top to allow steam to escape.

8. 8. Brush the top of the pie with beaten egg and sprinkle with flaky salt.

9. 9. Bake for 35-40 minutes, or until the crust is golden brown and the filling is hot and bubbly. Let cool slightly before serving.