Pre-heat the oven to 350°F.
In a small mixing bowl, beat the egg, then add the sour cream and mix together. Set aside.
In a large mixing bowl, sift together the flour,salt, baking soda, baking powder and allspice. Cut in the butter as if you were making pastry or pie crust and combine until the dough is fine and crumbly.
Add the brown sugar to the egg and sour cream mixture and stir to combine. Add this mixture to the flour mixture and stir to combine. If adding nuts, stir in.
Drop by rounded teaspoons onto a greased baking sheet. Bake for 9-11 minutes, until the edges are golden brown.
If you wish to put the dough in a cookie gun, refrigerate it for 30 minutes first, then bake the cookies for 7-9 minutes on a greased baking sheet. Cool on a wire rack.