Start by setting your oven to 400°F so it's fully heated by the time your pie is ready to go in. I always do this step first because a properly preheated oven keeps the crust from turning soggy. While it heats, I like to set out my butter so it's ready to melt quickly later.
Place your pie crust into the pan and crimp the edges however you like, whether that's a simple fork press or a fancier fluted pattern. I pop mine in the fridge while I make the filling so the butter in the dough stays cold. A chilled crust holds its shape much better once it hits the oven.
In a large bowl, whisk together the brown sugar, granulated sugar, melted butter, salt, eggs, flour, milk, and vanilla until everything looks smooth and glossy. I take my time here because a well-blended filling bakes more evenly. You shouldn't see any streaks of egg or lumps of sugar left behind.
Stir your chopped or halved pecans right into the filling mixture until they're evenly coated. I like using a mix of halves on top and smaller pieces throughout for the best texture in every bite. Pour this whole mixture into your prepared, chilled pie crust.
Wrap foil around the rim of the crust or use a pie shield to stop it from over-browning while the center bakes. I learned this trick the hard way after burning my edges on an early attempt. It only takes a minute and saves the whole presentation of your pie.
Bake at 400°F for 10 minutes, then lower the oven to 350°F and continue baking for another 30-40 minutes. I watch for the center to look just slightly jiggly while the edges look fully set. This two-stage bake is what gives the pie its deep color without overcooking the filling.
Let the pie rest on a wire rack until it's completely cool, which usually takes a couple of hours for me. I know it's tempting to cut in early, but the filling needs this time to firm up properly. Slicing too soon gives you a runny, messy piece instead of a clean one.