1. To prepare crust, add softened butter and pinch of salt to large mixing bowl. Mix with electric mixer until butter is creamy, about one minute. Add flour and cornmeal and mix again. Add egg yolks and mix again 30 seconds. Add ice water and mix until crust sticks together and there is no dry flour left. Pat crust with hands into a 1-inch thick disc. Wrap with plastic wrap and refrigerate for at least 1 hour and up to 24 hours.

2.  Preheat oven to 375F.

3.  To prepare filling, remove kale stems and chop kale roughly into 2-inch pieces. Place potatoes in large bowl of cold water.

4.  In large skillet over medium-high heat, add 1 tablespoon olive oil. Add onions, blistering them for 2 minutes until they begin to brown at the edges. Lower heat to medium and continue to cook about 8 minutes more until onions are soft. Add kale and pinch of salt. Saute until the kale is wilted and has shrunk in size by half. Add another tablespoon olive oil to kale while cooking if it's not wilting enough within 2-3 minutes. Remove from heat.

5.  While kale cools, remove crust from refrigerator. Grease 10-inch tart pan with a removable bottom or shallow 9-inch pie dish with butter. Press crust into tart pan with fingers until crust fills the bottom and sides of the dish. (This may take a little time and strength if dough is still cold.)

6.  Fill bottom of crust with kale and onion mixture. Drain potatoes and layer on top of mixture, overlapping slightly. Sprinkle with salt and freshly ground pepper. Top with grated gruyere. Bake 45 minutes or until the potatoes are fork tender and the top is browned. Let it cool slightly before removing from pan and serving.