Nan's Hot Fudge Sauce

For as long as I can remember my mom has made a summer dessert called Sundae in a Pan. An Oreo cookie crust, vanilla ice cream, peanuts, whipped cream, and a layer (never thick enough) of fudge sauce. Very much like a classic ice cream cake. The same fudge sauce functions equally well on its own served warm over ice cream.

• 10 tbsp unsalted butter
• 5 oz evaporated milk
• 6 2/3 oz semi-sweet chocolate chips
• 1 2/3 c granulated white sugar