In a small bowl, combine flour, baking soda, cream of tartar and salt. Mix well and set aside.

Beat together butter and brown sugar for five minutes, scraping down the sides of the bowl halfway through beating.

Add egg and vanilla and beat well.

Mix in flour and beat until combined.

Fold in morsels and nuts.

Place dough onto a piece of plastic wrap and shape into a log about 11-12" long. Roll the plastic wrap around the log and refrigerate for 4 hours.

Preheat oven to 375 and use a knife to cut 18, 1/2" cookie rounds. Place half of the rounds onto a baking sheet lined with parchment paper, keeping them 2" apart.

Bake for 10-12 minutes or until lightly browned. Let stand on pan to cool for 2 minutes before moving to a wire rack to cool completely.