In a large bowl, cream together the butter and brown sugar until smooth. Beat in the eggs. Combine the flour, baking soda, nutmeg, cinnamon and allspice; stir into the sugar mixture alternately with the buttermilk. Mix in the oats and raisins. Drop by rounded spoonfuls onto the prepared cookie sheet.
Bake for 8 to 10 minutes in the preheated oven. Allow cookies to cool on baking sheet for 5 minutes before removing to a wire rack to cool completely.