In Italy, where they make savory pies from almost every vegetable imaginable, kale is a popular choice, especially in Tuscany where it’s known as cavolo nero or black cabbage. Teamed up with pancetta, onion, garlic, ricotta, eggs, and grated pecorino, its slightly bitter flavor is complemented rather than hidden. This is a great solo dish or delicious accompaniment to plain grilled meat or fish.
For the dough, place all the dry ingredients in a food processor and pulse a few times to mix and aerate, add the olive oil and slowly add enough water until the dough begins to pull away from the sides of the food processor and looks like small peas. Remove the dough and knead for one minute then wrap in plastic wrap and set aside for 30 minutes.
While the dough rests combine all the ingredients for the filling in a large mixing bowl folding them together with a rubber spatula, make sure to squeeze as much water out of the kale as you can before chopping and adding to the filling.
On a lightly flowered work surface, roll out the dough so that it will hang over a 8 in x 11 in sheet pan by about 3 inches on all sides. Butter the sheet pan and transfer the dough and then the filling on top, fold over the dough ends and brush with egg wash (optional).
Preheat the oven to 350 degrees and bake for 30 to 45 min, until the the pastry turns golden brown and the filling fells firm.