Melt together the caramels, butter and milk in a double boiler; set aside. In a small bowl, combine flour, oatmeal, baking soda and salt; set aside. In a large mixing bowl, cream together butter and sugar until creamy. Gradually blend in flour mixture. Press mixture into the bottom of a 13 x 9-inch pan, reserving 3/4 cup for later. Bake for 10 minutes at 350 °F. When ready, pour caramel mixture over baked base, sprinkle with chocolate chips, nuts and reserved mixture. Bake for another 10 minutes. Cool thoroughly before cutting. Refrigerate if desired.