Preheat an oven to 325°F. Grease a baking sheet or line with parchment paper.
Combine dry ingredients and set aside. In a large bowl mix together the melted butter, pear puree, granulated sugar and brown sugar until light and fluffy. Add the egg, vanilla and egg yolk until well blended. Mix in the dry ingredients and stir in the chocolate chips.
Divide cookie dough into ⅛ cup portions and drop dough on to cookie sheets spacing them about 2 inches apart.
Bake for 15 minutes or until the cookies turn a golden brown.