In a large bowl, cream butter and sugar until smooth and fluffy. Beat in egg and extracts. Combine flour and dry pudding mix; gradually add to creamed mixture and mix well. Stir in chocolate chips.
Shape into 1-in. balls; roll in nuts. Place 2 in. apart on greased baking sheets; make a thumbprint in center of cookie. Bake at 350° for 10-12 minutes. Remove to a wire rack to cool.
For filling, beat the butter, confectioners' sugar, vanilla and enough milk to achieve desired consistency. Spoon into center of cooled cookies.
For glaze, if desired, melt chocolate chips and shortening; drizzle over cookies. Let stand until set.
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