Add all ingredients into a food processor and pulse until walnuts are finely ground.
Press into the pie plate and bake-off at 350 degrees for 15 minutes.
Banana Cream Pudding:
Combine the sweetener, coconut flour/xanthan gum, and salt in a large saucepan. Slowly add in the cream.
Meanwhile, separate the 4 egg yolks and 4 egg whites. Set the whites aside for use later. Beat the yolks slightly.
Cook over medium heat, stirring constantly until the mixture becomes thick and bubbly. Reduce heat and cook 2 more minutes.
Remove the pan from heat. Spoon some of the hot pudding mixture into the egg yolks and mix in order to temper them. Pour the egg yolks into the saucepan and mix it in well.
Place pan back on the heat and cook 2 more minutes. Remove from heat.
Stir in butter and vanilla until the butter is completely melted.
Set aside. If you need to, place a piece of plastic wrap on the surface of the hot pudding to prevent a skin forming (for instance, if you make the pudding ahead of time).
Peel the bananas and slice them into the bottom of the pie crust. You can put in as many as you want, but you should have a good thick layer.
Pour the pudding on top of the bananas until it almost fills up the pie crust.
Meringue:
Combine the egg whites, vanilla, and cream of tartar in a large bowl (or a stand mixer bowl).
Beat the egg whites on medium until soft peaks form.
Turn the mixer on high and slowly add in the sweetener
Beat on high for about 4 minutes or until you get stiff peaks. Makes sure all the sugar is dissolved by rubbing a bit of meringue in-between your fingers.
Spread the meringue on top of the pudding, sealing the edge to the pie crust.
Bake at 350° F. for 12-15 minutes--just long enough to toast the meringue. Let cool and eat chilled
Notes
If you need a lower carb option use the xanthan gum instead of the coconut flour and add banana extract to taste in the pudding and leave out the banana slices.Make sure the custard is very thick before taking it off the heat or it may not set when chilled. Also, make sure the coconut flour or xanthan gum dissolves all the way or the custard may be a bit chalky.If you choose the xanthan gum instead of the coconut flour add the xanthan gum very slowly a little at a time to the custard until you get your desired thickness. It's likely that you will not need the entire ¼ cup.