In a standing mixer on medium speed, cream together butter and brown sugar. Add eggs and beat until mixture is pale and thick - about 2 minutes. Beat in vanilla.
Reduce mixer speed to low and beat in flour, baking soda, salt, cinnamon, allspice and nutmeg. Incorporate raisins, dates and nuts (depending on your mixer, you may have to do this part by hand with a wooden spoon).
Drop cookies by tablespoonfuls onto a well-greased or parchment-lined baking sheet, about 2 inches apart. Bake 10-12 minutes, until edges are set but centres still appear moist. Cool on baking sheet 2 minutes, then transfer to wire racks to cool completely.
Store in an airtight container (up to 10 days) or freeze on a flat surface then transfer to freezer bags to store up to 3 months. Thaw at room temperature for 15 minutes before serving.