Mix the cookie crumbs, 8 tbsp butter and brown sugar with a spatula or your hands until the crumbs are moist. Press the crumb mixture into the bottom and up the sides of the greased pie dish. Cover the crust with plastic film and freeze while preparing the filling. (Or you can prepare the crust ahead and keep it frozen.)
Preheat oven to 350 degrees F.
Make the filling:
Melt the 12 tbsp butter in a heavy medium saucepan and add the brown sugar and corn syrup mixing well. Bring to a boil, while you stir. Boil for one minute. Stir in the pecans and Mexican crema or sour cream. Boil for three more minutes until the mixture thickens slightly. Remove from the heat. Add the chopped Mexican chocolate and stir until it melts and the mixture is homogeneous.
Pour the hot filling into the crust, evenly distributing the nuts. Bake until the filling is bubbly, about 10 minutes. Do not overbake or your filling might become hard. Take the pie out of the oven and cool completely before serving.