Things I've made in the past (but now I'm vegetarian and gluten free and minimal dairy. No onions , pulses or brocilli / cauliflower either I'm racking my brains here.)
For minimal assembly time , something like filo pastry with mushrooms? You can assemble the pastry (melted butter or oil) in shallow Yorkshire pudding tins, overlapping squares to look like stars, cover in clingfilm to keep from drying. Prepare a mix of mushrooms to fill.
Cheese choux pastry 'buns' baked in a ring (Delia recipe) filled with brocilli ( I love baked brocilli)
The Delia roulade is delish but needs alot of last minute assembly .
There was a Nut Roast I used to make too.
soften onions and garlic in butter
add white breadcrumbs, white cheese (feta or anything you like) thyme, chestnuts , artichoke pieces, eggs, lightly toasted white nuts (almonds,macadamia,cashews,brazils chopped)
Form into a roll, wrap in greaseproof then foil. Freeze till needed.
Bake from frozen, open the paper at the end to brown.
This was a Good Housekeeping recipe, probaby still on their website somewhere .
I used to do more elaborate meals pre DC. Now it's a Quorn Roast with all the vegetable extras. Because they're the best bit 