Emily Laurae

Walnut Tart Shell 
2 Using a stand mixer fitted with a paddle attachment, cream together butter and sugar for 2-3 minutes 
3 Add eggs, one at a time, until fully incorporated
4 Add flour, nutmeg and walnuts and mix until just combined making sure not to overwork the  dough 
5 Wrap dough in plastic and place in the fridge for 30-60 minutes  
18 Lightly flour your work surface, top of the dough, and rolling pin. Then use your rolling pin to roll out dough to a 12-inch circle (about 1/4-inch thick). Be sure to check if the dough is sticking to the surface below — add a small amount of flour when necessary and use a pastry scraper to prevent your dough from sticking too much.
7 Once your dough is rolled to the desired thickness (I prefer 1/4 inch), press gently into the bottom of your buttered tart pan. Poke the bottom of the tart LIBERALLY with a fork, and place in the freezer to chill for 20-30 minutes.
8 Preheat the oven  to 350° Fahrenheit
9 As this tart shell takes longer to bake than the pancetta filling, we will be par-baking the shell. This ultimately means that you will partially bake this tart dough lined with parchment paper and baking rice/beans acting as weights for 25 minutes. Remove the parchment and weights and continue as instructed below.  
Pancetta Gruyere Filling
12 Heat olive oil over medium heat in a saucepan or skillet
17 Once hot, add pancetta and cook until pancetta is slightly browned yet not completely brown or crisped. Remove cooked pancetta and set to the side
14 Add onion to the skillet and cook, stirring often, allowing it to slowly become tender over the  course of 15 minutes 
19 Meanwhile, whisk together your remaining ingredients - the eggs, sour cream and gruyere before finally mixing in the cooked onion and pancetta.
20 Pour mixture into the partially baked walnut crust, and continue baking for another twenty minutes, or until the filling has set and the edges of the tart dough have browned before removing from the oven and allowing to cool before serving.