Mine so far has to be Dark Chocolate and espresso Milk Stout. Ive only just done my first all grain, which is fermenting, so my experience is a little over a year of partial mash.
The above stout started as Brewers best Milk stout, with extra 2 oz of Chocolate malt. Added 12 oz of dark chocolate to the boil, and 4 oz of Cocoa Nibs to secondary for 10 days. also 5 shots of Starbucks espresso to secondary.