In large bowl, cream butter, peanut butter and sugars. Beat in eggs one at a time, beating well after each addition. Combine the flour, soda and salt; gradually add to creamed mixture. Chill 15 minutes.
Preheat oven to 350 degrees. Using a pastry bag fitted with a large star tube, pipe star shaped cookies onto sheet of aluminum foil cut to fit cookie sheets; placing cookies approximately 1 ½ï¿½ apart. Bake 6 to 8 minutes, cookies should just be set and should not brown.
When done, slide foil off cookie sheet and leave cookies on foil until cooled. When cool, spread bottom of cookie with approximately 1 teaspoon of nutella and top with a cookie that is close in size to the bottom cookie. Place cookies on a rack. Meanwhile, place chocolate and shortening in a freezer bag. Place in hot water in the top of a double boiler, leaving the top of the plastic bag open. When chocolate has melted, holding the top of the plastic bag, gently squeeze, so check that all chips have melted and to ensure the shortening is mixed inches Cut a tiny hole in one corner of the plastic bag. Place cookies close together on the cookie racks. Squeeze plastic bag gently and make a back and forth motion, creating thin chocolate drizzles on all cookies. Let cookies stand a few hours, until chocolate sets. Store in an airtight container, up to one week. Makes approximately 5 dozen cookies.
*Melted chocolate chips could also be used to fill cookies, just melt two cups of chocolate chips with one teaspoon of shortening and fill each cookie with approximately one teaspoon.