A very quick bake that I made over Christmas to be eaten on boxing day was Nigella Lawson's rocky road crunch bars. Really easy, really delicious:
I used digestives instead of rich tea biscuits (I bought the wrong type by accident, but they worked very well - although perhaps were less crunchy than the name of the recipe intends) and I added a small pot of cut up glace cherries to give a bit of chewiness.
Delicious. Moreish. May have been the cause of my stomach ache after I ate about 5 in a row...