Beat butter and 3 ounces cream cheese at medium speed with an electric mixer until creamy; gradually add sugars, beating until light and fluffy. Add eggs, 1 at a time, beating until blended after each addition.
Combine flour, baking powder, and salt; add to butter mixture, beating well. Stir in vanilla and pecans. Cover and chill 1 hour.
Drop dough by rounded tablespoonfuls 2" apart onto ungreased baking sheets. Bake at 350° for 10 to 12 minutes or until edges are golden. Cool 2 minutes on baking sheets; remove to wire racks to cool.
Beat or whisk together softened cream cheese, powdered sugar, and milk until smooth. Drizzle glaze over cookies. Let stand 1 hour or until set.