Instructions

1. Preheat oven to 375 degrees F. Line baking sheets with kitchen parchment paper or grease lightly.
    
2. In a medium bowl, stir together flour, baking powder, soda and salt. In a large bowl, beat together butter and brown sugar until fluffy. Beat in egg, vanilla and sour cream.
    
3. Add flour mixture to butter mixture, 1/2 cup at a time, stirring just enough to blend. Add nuts with the last addition of flour.
    
4. Drop by level measuring tablespoonfuls onto prepared baking sheets. Bake 8-10 minutes or until set and very lightly browned (do not overbake). Transfer to wire racks to cool. Prepare icing and ice when cool.
    
5. Top each cookie with a cashew half. Makes 3 1/2 dozen cookies. In a small saucepan over medium heat, lightly brown butter, stirring often to prevent burning.
    
6. Remove from heat and cool for a few minutes. Add vanilla and gradually add sugar, beating until smooth after each addition. Stir in just enough half-and-half to make an icing that can be spooned over the cookies.