COOKIES: Cream butter, gradually add powdered sugar, creaming well. Add vanilla, milk and salt; mix well. Blend in flour. mix thoroughly. Roll out dough, half at a time, to 1/8" thickness. Cut in 3" circles. Place on ungreased cookie sheet. Bake at 325 degrees for 12-15 minutes, or until lightly browned. Cool. CARAMEL FILLING: Combine caramels and milk in top of a double boiler. Heat until caramels are melted, stirring occasionally. Remove from heat. Add butter, vanilla and sugar. Mix well. Stir in pecans. Keep over hot water. Spread on cooled cookies. CHOCOLATE ICING: Melt chocolate pieces with evaporated milk over low heat. Remove from heat. Stir in butter, vanilla and sugar. Drizzle icing over caramel covered cookies and top with a pecan half if desired.