I bought a 375ml (1/2) pint of cheap vodka, and poured it over 4oz (actually 6 in total with 2oz added previously)) of crushed & roasted cocoa nibs. They didn't taste like much until after I roasted them, just like every chocolate producer you can think of. Anyway, I put the nibs and the vodka in a sealed container, and let it go for 4 or 5 days as well as being shaken every day. The flavor and aroma were amazing. I added both the vodka and the nibs together into 5 gallons into my secondary. I swirled (I didn't shake) the secondary every day for 6 days. The samples tasted the same on both of the last days, so I cold crashed it for two days, and the beer was clear, and the nibs were almost glued to the bottom it seemed. 375ml of vodka added to 5 gallons raises the alcohol by 0.7% or so, if it matters to you.
I almost forgot to mention; I added 3 tablespoons of pure vanilla and 8oz of Lactose before I cold crashed the beer, and on bottling day the flavor was great. I'll let you know in a month when I crack one open.