what do add to shepherd's pie to boost it?

[NoahVale]

as a child my dm would put baked beans in, but i am not going to do that
i think carrots, celery mushrooms
any other suggestions?

I tend to add sweetcorn and peas.

I might mash the potatoes with some parsnips or carrots.

I put a tablespoon of coarse grain mustard in the mash

Bisto original gravy powder and a tin of baked beans!