Cream butter and shortening; gradually add sugars, beating well at medium speed of an electric mixer. Add eggs and vanilla, beating well. Combine flour, soda, and salt; add to creamed mixture, mixing well. Stir in chocolate morsels. Drop dough by heaping teaspoonfuls onto ungreased cookie sheets. Bake at 190ºC or 9 to 11 minutes. Cool slightly on cookie sheets; remove to wire racks to DOUBLE CHIP COOKIES: Prepare Best-Ever Chocolate Chip Cookies, using peanut butter morsels or butterscotch morsels and semisweet chocolate morsels instead of 1 (12-ounce) package semisweet chocolate morsels. Jumbo Chocolate Chip Cookies: Prepare Best-Ever Chocolate Chip Cookies, dropping them onto ungreased cookie sheets by quarter cupfuls. Lightly press each cookie into a 8 cm circle with fingertips. Bake at 180ºC or 15 to 17 minutes. ----