Step 1

In a medium bowl, stir together the sweetened condensed milk and vanilla. Set aside.

Step 2

In the bowl of a stand mixer or a large bowl with a hand mixer, beat heavy cream on high until soft peaks form, about 2-3 minutes. With a rubber spatula, gently fold condensed milk mixture into whipped cream. If using peanut butter chips, fold them in until well combined.

Step 3

Place peanut butter in a small microwave safe bowl and heat on high for 30 seconds. Pour 1/3 of the ice cream base into a 9x13 inch loaf pan. Drizzle 1/3 of the melted peanut butter on top and swirl gently with a knife. Repeat the process until all ice cream base and peanut butter is gone. Cover with foil and place ice cream in the freezer to set for 4 hours or overnight.