Grind the venison and the pork fatback into the bowl of an electric stand mixer that is sitting in an ice bath.
Scoop out 1/3 of the ground venison mixture and place it in a separate bowl. Add the livers, garlic, onion, optional spice mix, salt and pepper. Grind this into the same both as the venison and pork fat grind from step 3. Place in the refrigerator until its thoroughly chilled (30 minutes to an hour).
In a clean bowl, add the flour, heavy cream, eggs and brandy. Whisk until it is thoroughly blended with no lumps. Pour this into the mixing bowl with the ground venison mixture that's in your refrigerator. Now is the time to add the optional diced ham and toasted nut garnishes if you are using them.
Attach your mixing bowl to your stand mixer fitted with the paddle attachment. Mix on medium speed until all of the ingredients are fully incorporated and the mixture is sticky. This will take around 1 to 1 1/2 minutes.
Now is a good time to check for seasoning. You can fry a small piece in a pan or poach in water. Taste and adjust the seasoning as needed. Keep in mind that this will be served cold or at room temperature. And cold food needs more salt.