Line a 6-quart oval slow cooker with parchment paper (12.5 inch x 16 inch). Press the paper down into the slow cooker to create an outline of the bottom of the slow cooker.
Remove parchment paper and place unrolled pie crust onto the parchment paper (lining it up with the creases from the outline in the parchment paper). Gently roll up the edges of the pie crust and make small indentations to help the crust stick to the parchment paper and to keep in the filling better.
Place parchment paper/pie crust into slow cooker (pastry should extend 2 to 3 inches up the sides). Bend and fold the pastry as needed to get it to fit properly.
In a bowl combine the eggs, corn syrup, sugar, melted butter, cinnamon and vanilla. Whisk until smooth. Stir in 1 cup of the pecans.
Gently pour batter into crust in the slow cooker. Then top with remaining cup of pecans. Placing them evenly in a pattern to make a nice presentation.
Place a layer of paper towels on top of the slow cooker then cover with the lid. Cook on high for 3 to 3 ½ hours or until filling is puffed and set. Turn off slow cooker. Let stand, uncovered, 1 hour.
Cut and serve straight from the slow cooker. Or gently lift the parchment paper out of the slow cooker, then slice and serve.
If you like smaller pieces of pecan in your pie, be sure to chop up at least one cup before mixing. Updated to add: Some folks emailed me and expressed concerns that they feel their slow cookers 'run hot' and are afraid the sides would burn before the middle was done. You can cook this on low. And I really recommend using the parchment paper as it creates a barrier between the pie and the slow cooker insert. If you cook it on low, you'll just need to double the cooking time.