2 cups (60 g) coarsely chopped kale leaves, stems removed
In a food processor, combine the flour, baking powder and salt. Add the butter and pulse until the butter forms pea-sized pieces. Add the water and pulse again until the dough just begins to form. Add water, if needed. Remove the dough from the processor and shape into a disc.
On a lightly floured surface, roll the dough out into a 1/8-inch (3 mm) thick rectangle. Line a 13 x 4-inch (33 x 10 cm) tart pan with a removable bottom. Remove any excess dough. Refrigerate for 30 minutes.
With the rack in the middle position, preheat the oven to 400°F (200°C).
In a non-stick skillet over medium heat, soften 2 of the onions in 2 tbsp of the butter. Let cool. In a bowl, beat the eggs with the cream. Add the cheese. Season with salt and pepper. Layer the onions on the crust. Pour the egg mixture over the onions.
Bake for about 30 minutes or until the crust is golden brown.
In the same skillet over high heat, brown the remaining onion, the ham and kale in the remaining butter for 3 minutes or until the kale has wilted and the ham is heated through.
Unmould the tart and slide onto a cutting board or serving plate. Top with the ham and kale mixture. Serve hot or cooled.