Combine the milk and sugar in a saucepan and cook over medium-low heat until thick, stirring all the while to dissolve the sugar crystals. Bring this to what Loretta called a “molten boil”, raising the burner temperature slightly if needed. In candy-making terms the ideal fudge temperature is 235˚F to 245˚F.
You can test this without a thermometer by dropping a tiny bit of the mixture into a bowl of cold water. If you have a little ball of candy that you can flatten with your fingers then it’s ready. This is called the soft-ball stage. If it’s too sticky or if it doesn’t form a ball then you haven’t hit the right temperature.
Once you have the right temp you have “work quickly” since it will set up very fast. Add in the butter, vanilla, and peanut butter and stir well. Peggy says you also can add in 1/2 cup of maple syrup for an extra hit of flavor. She also says you can use either creamy or crunchy peanut butter and that her mom used both at different times.
Pour this into a greased 8″x8″ pan. Then top with crushed peanuts before it sets. Peggy crushes the peanuts with the bottom of a ramekin on a butting board. It looks a whole lot easier than chopping them! The finishing touch is to sprinkle a little salt on top. Then you have to let it set at room temperature for a couple of hours before cutting into squares.