Before getting started, line a 9-inch pie plate with a homemade pie crust if you're using homemade. Keep in mind that you will also need a second crust for the top.
Start by thinly slicing the onions with a large knife, and then chop up the celery, carrots and potatoes. Mince up the garlic if using cloves.
Once the vegetables are prepared, layer everything in the slow cooker. You want to make 3 total layers, adding 1/3 each of the stew meat, veggies, butter, water, flour, cream, salt & pepper to each individual layer.
Cook on high for 4 hours, and then turn it down on low for an additional 1-2 hours, or ’til the onions are dissolved and a thick gravy forms. Be sure to give everything a stir periodically as it cooks.
Once your filling is fully cooked, stir in the cumin, cinnamon and nutmeg 'til well combined.
Pour the precooked filling into your unbaked pastry shell.
Add your top crust to the pie, and use a knife to cut 2 1” slits, criss-crossed in the middle. This should create an X-shaped hole in the middle of the top crust through which excess steam can escape, which prevents a soggy crust.
Bake at 425ºF for 20-25 minutes, or ''til the crust is golden-brown.
That's it! Serve and enjoy with all your favorite side dishes.