Adapted from Gourmet
1 2/3 cups whole milk
1 cup creamy peanut butter (such as Jif or Skippy - natural PB doesn't work as well)
1/2 cup plus 1 tablespoon granulated sugar
2 teaspoons pure vanilla extract
3 tablespoons water
1/4 cup loaded with semi-sweet chocolate chips
While the ice cream is turning, make the chocolate sauce. In a small saucepan, add the water and remaining tablespoon of sugar, stirring, until sugar dissolves. Add the chocolate chips, whisking the sauce until smooth, and cool to room temperature.
Spread one third of the frozen ice cream in a 2-quart container and top with one third sauce
(we used a deep container but it will be easier to swirl if you use a flatter plastic container) . Layer remaining ice cream and sauce in same manner and, with a rubber spatula, swirl sauce and ice cream together. Do not over swirl or the chocolate and peanut butter ice cream will blend too much together. We are wanting a ripple of fudge.
Freeze the ice cream, covered with plastic wrap, until hard, at least 3 hours.