1 1/2cupsdried cranberries or fresh cranberriesoptional; see notes to use fresh
Place Brussels sprouts into a 6-quart slow cooker (see recipe notes if using a 6-quart slow cooker).
Stir in the maple syrup, olive oil, salt, and pepper.
Cover and cook 2 1/2 hours on low or 1 to 1 1/2 hours on high, until the Brussels sprouts are crisp-tender but still a little too chewy to eat. Stir once halfway through to redistribute.
Stir once more, then recover and cook until the Brussels sprouts are completely tender (but not mushy), about 15 additional minutes on high or 30 additional minutes on low.
Stir in half of the feta cheese and cranberries.
Sprinkle the remaining feta on top. Serve warm.
TO USE FRESH CRANBERRIES: Stir in the fresh cranberries in Step 3 when redistributing the Brussels sprouts.
TO HALVE THIS RECIPE: Use a 3- or 4-quart slow cooker.
TO MAKE AHEAD: Chop all of the Brussels sprouts and place in the slow cooker. Store refrigerated. When ready to cook, proceed as directed. (You may need to add a little bit to the cooking time since the slow cooker will be cold.)
TO STORE: Refrigerate Brussels sprouts in an airtight storage container for up to 3 days.
TO REHEAT: Gently rewarm leftovers in a Dutch oven on the stovetop over medium-low heat or in the microwave.