Grease an 8-inch round cake pan with softened butter.
Pour in the chocolate and butterscotch chips, condensed milk and vanilla into a medium saucepan. Put the pan on the stove and turn the heat to low.
Cover the empty condensed-milk can with plastic wrap and put it in the center of the round cake pan.
Stir the chips and milk until they melt together, about 3 minutes. Have a GH (Grown-up Helper) move the pan off the stove if it’s too heavy. Place the pan on a pot holder so it does not burn the kitchen counter. Stir in the nuts and raisins.