Add the butter and cream cheese to the bowl of a stand mixer and mix with a paddle attachment until combined. Add the flour to the bowl, sprinkle with the kosher salt and combine on low speed until just combined and the flour is in pieces the size of peas.
Dump onto a clean surface sprinkled with flour and mold into a disc. Cover with plastic wrap and chill for at least 30 minutes.
Transfer the dough to a lightly floured surface and roll out into a 15-inch circle, moving the dough in a circular fashion each time you make a pass or two with the rolling pin so it doesn't stick. Add more flour under the dough as needed.
Carefully roll the dough around the rolling pin and transfer to a 9-inch pan with a removable bottom. Gently press into the pan and leave at least a 1/2 inch or more overhang. Prick the bottom of the dough with a fork. Freeze in the pan for 2 hours or overnight.
In a large skillet, cook the bacon over medium heat stirring occasionally until the bacon is lightly browned. With a slotted spoon, transfer the bacon to a plate covered with a paper towel for the bacon to drain and cool.
Pull the frozen pie crust from the freezer and line it with parchment paper and fill the entire pan with the uncooked beans to the very top of the pan. Bake for 20 minutes or until the crust is lightly golden brown.
Remove the beans and parchment paper and then layer the partly cooked pie crust with the cheese, bacon and the spinach and leek mixture, reserving 1 tablespoon or so of each ingredient.
Add the eggs, milk, yogurt, white pepper and ground nutmeg to a blender and blend until frothy. Pour the custard over the layered ingredients in the pan. Sprinkle with the reserved ingredients.
Reduce the oven temperature to 325 degrees F and bake for 1 1/2 hours or until the top is lightly browned and custard is just set in the middle (165 degrees F). If the top is getting too browned and inside isn't yet cooked, tent with aluminum foil and cook in additional 10 minute increments.