In a food processor or with an electric mixer, incorporate butter and sugar. Mix in egg and vanilla. Mix in flour and salt. Drop a heaping teaspoon on a greased baking sheet, permitting enough space for the cookie to spread about 3 1/2 inches. Press about 3 jelly beans into each cookie. Bake in a preheated 350 degrees for 8 to 10 minutes or until edges just begin to brown. Let cool on a baking rack. Store in a cookie monster-proof container.