Whisk together all ingredients for filling, mix well and pour mixture into your unbaked pie shell.
Bake at 425 for 10 minutes then reduce heat to 350F and bake additional 45 minutes or until set. Cool.
To Make the Topping
Combine the butter and 1/4 cup of brown sugar in a saucepan; cook over medium heat, stirring until the sugar is dissolved.
Add the nuts and 3 tablespoons of bourbon, stirring to coat the nuts. Spoon the mixture over the pie.
To Flame the Pie (Optional)
Heat the 2 tablespoons of bourbon in a small saucepan, just long enough to produce fumes (do not boil); remove from the heat, ignite with a match and pour over pie. Serve pie when flames die down. (Or just heat the bourbon and let it simmer for a minute or two to burn off some of the alcohol before pouring on top of the walnuts)