Earlier this year I posted the easy recipe for Peanut Butter Fudge (click for a recipe). It only takes four ingredients, and is prepared in minutes! And it is soooo tasty.
I use a sweet milk chocolate in morsels. It is chocolate that melts easily, and making the fudge fast to form. If you use a chocolate that will take more time and higher temperature to start melting, be very careful with the condensed milk, so it doesn't burn.