Preheat the oven to 350˚F.
On a lightly floured surface, roll out the pastry to a 10-inch circle and line a tart pan or pie plate, trimming the edge flush with the plate and crimping it, if you like. Refrigerate while you make the filling.
In a large skillet, cook the chopped bacon until crisp; transfer to a bowl with a slotted spoon.
Add the onion to the pan and cook for 4-5 minutes, until golden. Add the kale for the last minute, just letting it wilt.
Meanwhile, in a medium bowl, whisk together the eggs, cream, green onion, salt and pepper.
Stir in the grated cheese.
Spread the bacon mixture into the bottom of the pastry shell and pour the egg filling over top.
Bake for 45 minutes, or until golden and set.