I'm serving with roasted Brussels sprouts and wild mushrooms

Most that come peeled (in cans or vacupacs) are already cooked.
If it's those you are using, you need only a few minutes (maybe 10) in a reasonably hot oven or under a grill to warm them up, or a bit longer if you want them crunchy or crusty.
If you are preparing from raw, I would boil them first (in water or broth for savory dish, in water or milk for dessert) until tender (maybe 20 min), then finish in the oven or under the grill.
Just curious, how are you serving them?