Sour Cream Sugar Cookie

In a bowl cream butter , sugar. Add in egg sour cream, vanilla and zest. Combine flour, baking soda and salt; gradually add to creamed mixture. Shape in a round, cover and chill for an hour. When ready flour work surface with confectioners sugar, roll out to 1/8 thickness, cut with cutters. Place in parchment lined cookie sheet. Bake at 375 for 8-10 min. Cool on wire rack. For icing, combine milk and pudding mix until smooth:set aside. In a bowl cream butter. Beat in pudding mixture. Gradually add sugar, vanilla and desired colourings. Beat til fluffy. Frost cookies.