preheat oven to 300 degrees. In double boiler, melt semisweet chocolate, set aside to cool to room temperature. in small bowl mix flour, baking soda and salt.
In medium bowl, mix brown and granulated sugar, then add butter and beat until well combined. Add the beanut butter and beat until smooth. Add eggs and vanilla and beat until combined. Add flour mixture and the mild chocolate chips and beat until no streaks are visible.
Pour in the mealted chocolate and mix partial with wooden spoon until marbled. Drop dough in Tablespoone mounds about 2 inches apart on ungreased baking sheet. Top cookie with whold peanut.
Bake for about 20-25 minutes until set, but still soft. Cool on the cookie sheet for about a minute then transfer to wire rack to cool completely.