My mom always used canned yams, draining and adding butter, brown sugar, cinnamon, and marshmallows on top. No one ate them except her yet she made them every single year that she hosted.
I grew up & stopped using canned. Now, hosts ask me to bring the sweet taters and I never bring home leftovers. (If by some odd chance there is anything leftover, guests & hosts alike ask me if they can 'help me out by taking home some leftovers'...I've given up and just make two batches so I can leave one at home!)
Get real sweet potatoes. These are pretty small, come in bags around here, and are usually found in either an orange or yellow fleshed option. These are not the huge yams that most people think of. Ask your grocery department manager to get them for you next time you have time. The huge yams already on display will work in a pinch, but the difference is big enough to bother with if you have the time. Slice super thin, using a mandoline or food processor so that they are totally even. Layer them like you would for scalloped potatoes, overlapping each slice by about 1/2, and fill the pan to just beyond totally full. It'll slump down some, but not too much if you have the slices layered nice and close. Take a whole stick of real, salted butter & melt it. Mix in 1/2 cup of white sugar, 1/2 Tablespoon molasses, and 1/2 each vanilla & almond extract. You can add a teaspoon or so of lemon or lime juice if you want a nice bright flavor with depth, but it's just icing on the cake at this point. Pour over the layered potatoes and sprinkle with pecans, walnuts, or a combination. Bake at 350 until a toothpick in the center goes in & out without dragging whole slices of potato with it, totally tender. You can serve at this point, or continue as follows. Top with marshmallows, if there are some diehard 'mallow fans in the guest list, at the very end. You'll want to crank the heat up to 450 or so, so that the 'mallows brown quickly. If you can loosely cover the dish before serving, this will help melt them too, just be careful they don't stick to the foil and disappear at the unveiling, lol.