The method of cooking is called "Butt over Brisket" is a great way to utilize a fatty cut like a pork roast, aka Boston butt, to baste your beef brisket. Just think of it as a little bacon-y flavor on top of your brisket - it works for burgers!
This method makes good use of upright (UDS, WSM, etc), cabinet-style or other vertical smokers. You simply need to cook a butt on a grate overtop of your brisket (or two if you have a full packer brisket). As the pork butt cooks the drippings will drip on the brisket keeping it moist. I’d recommend cooking the brisket fat-side down with this type of cook – if you think about it this will have you covered on both sides. The drippings from the Boston butt on top and the fat on the opposite side to shield from the heat. Experiment with both and see what works best with your smoker.
The finish times shouldn’t vary too much from your normal cooks. Put your meats on at the same time. Cooking times will depend upon your smoker and your specific cuts, but should be about the same times as each cooked on their own. Some find that their butts still take a few hours to finish after the brisket is removed. This is just fine – simply wrap with foil, towels and hold in a cooler until the pork is finished. This extended resting time for the brisket is helpful in tenderizing this tough cut.
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