beat 3/4 cup butter and cream cheese in medium bowel; add flour and 1/4 cup sugar, beating until well blended. cover; refrigerate about one hour or until dough is firm. shape dough into 1-inch balls; press balls onto bottoms and up sides of about 36 small muffin cups. (1 3/4 inches in diameter)

heat over to 350°F. combine egg, remaining 1/2 cup sugar, melted butter , lemon juice, and vanilla extract in small bowl; stir until smooth. stir together milk chocolate chips and peanut butter chips. set aside 1/3 cup chip mixture; add remaining chips to egg mixture. evenly fill muffin cups with egg mixture.

bake 20-25 minutes or until filling is set and lightly browned. cool completely; remove from pan to wire rack.

combine remaining 1/3 cup chip mixture and shortening in small microwave-safe bowl. microwave at MEDIUM for 30 seconds; stir. if necessary, microwave additional 10 seconds at at time, stirring after each heafing , until chips are melted and mixture is smooth when stirred. drizzle over tops of tassies.