Step 1

In a large, heavy saucepan, heat the milk, brown sugar and salt until bubbles form around the side of the pan. Whisk a small amount of the hot mixture into the egg. Return all to the pan, whisking constantly.

Step 2

Cook and stir over low heat until the mixture is thickened and coats the back of a spoon. Remove it from the heat and whisk in the peanut butter. Quickly transfer it to a bowl, place it in ice water and stir for 2 minutes. Stir in the cream and vanilla. Press waxed paper onto the surface of the custard. Refrigerate it for several hours or overnight.

Step 3

Fill the cylinder of an ice cream maker 2/3 full and freeze according to the manufacturer’s directions. Transfer ice cream to freezer containers, allowing headspace for expansion. Freeze until firm, two to four 4 hours.