Preheat oven to 375 and line cookie sheets with parchment paper
Cream together the peanut butter, shortening, brown sugar, milk and vanilla; mixing well
Add the egg and beat in until just blended
In a separate bowl sift together the flour, salt and baking soda
Slowly add the cream mixture until just blended
Roll into 1" balls, slightly flatten with your hand then criss-cross with a fork (dip fork in flour to prevent sticking)
Bake for 8 minutes then cool on cookie sheet for 2 minutes before removing to wire rack to cool completely
Cookie will firm up a bit when they cool - do not overbake