Preheat oven to 350 degrees F. Line two cookie sheets with nonstick foil or parchment paper.

In a large mixing bowl, beat the butter and brown sugar until creamy. Beat in the peanut butter, salt and vanilla, scraping sides and beating until smooth. Beat in the egg, beating just until it is mixed.

Stir in the baking soda until it is thoroughly blended, then stir in the flour. When flour is blended, stir in the chocolate chips.

Using a level teaspoon of dough, scoop up dough and shape into balls. For larger cookies, use a level tablespoon. Press the balls into circles and arrange about 2 inches apart on the cookie sheets. If desired, sprinkle half the dough rounds with sparkling sugar.

Bake one sheet at a time on center rack for 8 to 10 minutes (or longer if making larger cookies) or until cookies are golden brown around the edges. Let cool on cookie sheet for 5 minutes, then transfer to a rack to cool completely. When cookies are completely cool, turn half of them upside down and spread with a little chocolate hazelnut spread and a little peanut butter. Cap with the remaining cookies