Super-thick chocolate fudge in a single mixing bowl!
Line a square 8x8 inch baking dish with foil.
Chop up the chocolate and place it in a big bowl along with the condensed milk. Make sure the bowl is microwave safe! Microwave the bowl on high for 2-3 minutes, pausing to stir once or twice. Take the bowl out of the microwave and stir the contents until it's completely smooth. Stir in the vanilla and walnuts, then spread that stuff in the prepped pan.
Let the pan chill in the fridge for 2 hours to firm up, then cut the fudge into squares.