CRUST: In a large bowl, combine the flour, salt, and powdered sugar. Stir. Add in the butter and using a pastry cutter, cut it into the dry ingredients until the mixture resembles coarse bread crumbs. In another separate bowl whisk together the egg yolk and water until smooth (reserve this bowl for later). Pour egg yolk mixture into the center of the dry ingredients and stir with a wooden spoon until combined as much as possible. Gently knead with your hands to form a crust (add extra tablespoon of water IF needed). Handle the dough as little as possible and once it's formed into dough, wrap it in plastic wrap and gently flatten into a small disc. Refrigerate for (at least) 30 minutes to allow the gluten to relax before rolling. You can make the crust ahead of time and refrigerate for 1-5 days.
TOAST PECANS: (Melt your butter right now so it has time to cool to room temperature.) Preheat the oven to 350 degrees F. Spread full pecans over a rimmed baking sheet and toast them for 8-10 minutes or until fragrant and lightly browned. Remove and let cool. Separate toasted pecans reserving 3/4 cup for the top of the pie. Chop the remaining 1 and 1/4 cups to add into the filling mixture.
FILLING: Combine the ROOM TEMPERATURE (it's very important all ingredients are same temperature for this filling) egg yolks, syrup, brown sugar, and cream in a large bowl. Whisk until smooth. Once the melted butter is completely to room temperature gradually drizzle it in while whisking constantly. Fold in the chopped pecans.
ASSEMBLY: Roll out the pie crust on a lightly floured surface. Turn the dough about a quarter turn after every few rolls until you have a 12 inch circle of dough. Use the rolling pin to lift up the dough and gently place place into a 9-inch pie pan (preferably glass or ceramic; avoid metal). Gently tuck it in with your fingers, making sure it is smooth and then crimp the edges of the crust. Chill for 15 minutes in the refrigerator or freezer (don't skip this step!).
ASSEMBLE CONT.: Preheat the oven to 350 degrees F. Pour the prepared filling right on top of the chilled crust (you don't need to blind bake the crust) Press the remaining 3/4 cup whole pecans on top. Place the pie on a lined sheet pan. Use a pastry brush to brush any tiny remains of the egg yolk and water mixture (from the reserved bowl; you didn't need to leave some specifically, there should just be a bit leftover) onto the crust. Place into the preheated oven.
BAKE: Bake for 40-55 minutes, or until the filling is set. The filling is "set" when it's very slightly jiggly in the center. It should not slosh around at all. If it is sloshing, don't hesitate adding it back into the oven for another 10-20 minutes (baking times can greatly vary with pecan pies). IF the edges of the crust begin to brown, cover with a pie shield. Once the filling is set, remove the pie and let cool completely on cooling rack, 3 to 4 hours, before slicing. Serve warm with vanilla ice cream.