Similar to the melting snowman cookies above, DD has made marshmallow snowmen for her entire class in the past - a massive marshmallow stacked onto a normal sized marshmallow (using white chocolate as the "glue"), then a large chocolate button (as the brim of a hat) and a mini marshmallow on top again (which I think may have been dipped in melted milk chocolate), facial features on the normal sized mallow and buttons on his coat on the massive one, were made using a cocktail stick dipped into the milk chocolate as a "paintbrush".
And something I used to give DD early in December, but could be useful for Christmas Eve activity, was a shoebox full of different coloured strips of paper (I just got different coloured sheets of A4 and cut them to the same size) and a roll of sellotape in a dispenser. She could spend 5 minutes when she was bored and put it back down on a regular basis, or dedicate 30-60 minutes to it working together, to make paper chains that we would then hang on the ceiling in the hall. We used to do it together when she was very young, but as she got older, it was handy to have to one side that she could take out herself after school etc and sometimes do together but often just herself while I worked on dinner etc. And over the few weeks in December, she'd usually end up with a decent length of chain!
On Christmas Eve every year, DD makes cookies for Santa. While we might be a bit more intricate with rolling out and cutting shapes on other days, Santas' cookies are always the kind of dough that is rolled into a log and sliced into rounds for baking. This is a relatively easy one to make, but also one that freezes well so I always have a half batch from earlier in Nov/Dec in the freezer, and that gives flexibility to allow us bake from scratch if we have time and are relaxed, but if we've been busy with other things and adults need the kitchen to prep dinner and things for 25th, DD can do it easily at the table using the frozen log (we thaw it for 30 minutes to be soft enough to cut) instead.
It can also be a good time to finish wrapping their presents - that they are giving to people (not including to you) - as that usually requires assistance. DH will have to help with yours later! (Or cut the paper to an approximate size, leave lots of bits of sticky tape pre-cut and on the edge of the table, and leave them to it!).
When DD was that age, as I always have to go into work for an hour or take a whole day as leave, she came to the office with me while DH had a quiet coffee on the shopping street nearby - we met him later and would get any last minute things in M&S that we needed (including DD picking out her birthday cake for 26th!), and any other shopping we had left, before a nice family lunch in town. Just a sandwich and coffee, but DH and I had started to switch off and relax, and we could enjoy people-watching etc.
Then we head home and prep for 25th, peel veg and potatoes, make stuffing, those kinds of jobs. Dinner on 24th is always "platter" - lots of nice nibbly things laid out in the middle of the table for people to help themselves. Cooked and cured meats (ham, salami, parma ham, braseola, spiced beef etc), and fish (smoked salmon, prawns, squid rings), maybe some pate. A few hot things like some sausage rolls (HM or M&S) or prawns in pastry or other party food bits (usually M&S). Hummus and salsa, with carrot sticks, pepper sticks, breadsticks to dip. Cherry tomatoes, olives, salad leaves. Nice sourdough bread or some good crackers. The Christmas cheeses are opened. Not loads of any one thing (except cheese), but a few regular favourites and some special treats that we love but only get occasionally.
After dinner, we go into the sitting room and the youngest (i.e. DD) lights the Christmas candle. It's an Irish tradition, and should go in the window to show that there is "room in our Inn" for any weary travellers, but we want to be able to close the curtains so it goes on the mantle instead. But we always have a few minutes of quiet reflection together, remembering the good and bad things of the year just finishing, and the people we love who have died, and finish with a short prayer.
Then we get out our Christmas Eve Hamper (that I always make and everyone knows it's me, not the Elves). There are new PJs for everyone, nice hot chocolate, a Christmas beer for DH, lush bath bombs for DD and I (and a festive shower gel for DH if we see one we think he'd like), DD's stocking, her plastic glass and plate (from toddler years) with Santa on them, and her snowman covered hot water bottle (in use all winter for years now), and the family copy of "Twas the Night before Christmas". DD puts out her stocking and gets the cookies for the plate, fills the glass with milk. She then has her Christmas bath and puts on her new PJs, coming back downstairs for her hot chocolate and a spare cookie before I read the book to her in bed tucked up with the hot water bottle. Even though she no longer believes in Santa and is now 13, it is still an important part for her!
Christmas Day, after the stocking has been inspected, breakfast involves freshly squeezed orange juice (and lots of coffee for adults!), but also freshly baked pastries. Jus Rol do croissants, pain au chocolat and pain au raisin in tubes to make up in minutes at home - DD used to help with this (and brushing with egg wash to make them golden and crispy), and now takes complete control. Or M&S sell bags of different pastries which are ready to just throw on a baking tray from frozen, no prep involved at all.
We usually also have some freshly chopped fruit, and DD is usually involved in this as well.
We always go to mass on Christmas morning, so showers and nice clothes after breakfast, and we have to call to family afterwards before going back home. When we get in, we start by turning on tree lights, some music and the oven, putting a tray of M&S party food in the oven, while we prep the turkey and get that cooking, get the fire lit, and generally get ourselves organised. Then everyone gets a nice drink (DD gets something like a J2O or a fizzy drink, we might make a G&T or open a bottle of nice wine) and the nibbles are put on a plate, (candles are lit in sitting room) and we go to open presents around the tree. This takes a while as we are in no rush, and we open them one at a time (but spread them around so it's not one person opening all theirs before the next person gets to start). We pause as we pop in and out of the kitchen as necessary to do the next jobs, and once the presents are all opened, might turn on the tv or play a game together, or DD often just played with her toys while we finished off and chatted.
We eat in the evening (we used to aim for 6pm, it's a little later nowadays, but were always eating before 8pm) and DD has generally gone to bed after that. We might watch tv for a short while before bed ourselves (and I always have to strip the leftover turkey meat from the carcass for the fridge).
On the morning of 26th, I put the carcass on with veg etc to make stock and we all go for a long walk (usually the local park with a steep hill in the middle, sometimes further afield). Then we go home and prep for visitors later, when we do mulled wine and party food nibbles and turkey sandwiches and a birthday cake for DD. We give her her present before others arrive, as it's a rather rolling entertainment - family come in the afternoon, and some neighbours come in the afternoon if they can but some come in the early evening after their own family commitments and often stay until late night (we're a sociable street!). So it is a nice but relaxed celebration.