Heat your oven to 180°C/Fan 160°C/Gas 4. Fill a pan with hot water and add a pinch of salt. Cover and bring to the boil. Peel and chop the potatoes into small chunks. When the pan is boiling, add the potatoes and simmer for 20 mins.
While the potatoes simmer, peel and finely slice the shallots. Trim the bottoms off the Brussels sprouts and finely slice them. Peel and crush the garlic cloves.
Pop the cherry tomatoes on a baking tray and slide into the oven. Roast for 10-15 mins till the tomatoes are soft, a little charred and start to burst.
Set a griddle pan or heavy-based frying pan on the hob and leave it for 5-10 mins to heat up – you want it to be smoking hot. Melt half the butter in a separate deep frying pan or wok. Add the shallots and fry over a medium heat for 3 mins till starting to brown.
Stir the garlic and Brussels sprouts into the buttery shallots. Season with a pinch of salt and pepper. Pour in the cream, stir to mix and turn the heat down to low to gently warm through cream and cook the Brussels sprouts. Let it gently cook for around 4-5 mins.
The potatoes should be tender by now, so drain them and tip them back into the pan. Add the remaining butter and some salt and pepper and mash together. Cover with a lid and set aside to keep warm in the pan.
Rub the steaks with 1 tsp oil each and some salt and pepper. The pan should be really hot by now. Add the steaks and fry for 30 secs-1 min on each side, depending on how well done you like the steak. Slide the steaks onto warm plates and leave to rest for 1-2 mins.
Grate 1/4 of the nutmeg over the Brussels sprouts, stir and then taste. Add more salt, pepper or nutmeg if you think it needs it.
Scoop the mash onto warm plates with the steaks. Spoon the creamed Brussels sprouts onto the plates, add the roast cherry tomatoes and serve.