Sweet Potato Mash, Chicken & Mushroom Sauce

1 Large Sweet Potato (roughly the length of your forearm)
2 Small potatoes
1 clove of garlic, crushed
6 sage leaves
dash of milk
pepper
salt

1 large diced onion
olive oil
1 bay leaf

4 chicken thigh fillets
8 button mushrooms, sliced (these could be replaced with something like Swiss Browns or another mushroom with more kick in it)
5 sprigs of thyme (just the leaves)
1 cup of chicken stock
1 tsp of cornstarch

1. Peel and slice the potatoes. Put the potatoes, sage leaves and clove of garlic in a pot of heavily salted cool water and bring it to the boil.
2. While the potatoes are cooking, heat a good slurp of olive oil in a fry-pan and cook the onions and bay leaf until the onions are translucent.
3. Into the onions, put the chicken fillets out flat and remove the bay leaf.  Brown them in the pan.
4. Remove the chicken and then put in the mushrooms.  When they are starting to soften and change colour, put in the stock to deglaze the pan. When the pan has deglazed, add in the cornstarch to thick the sauce up.
5. Drain the potatoes (leaving in the garlic), take out the sage leaves and add in a good amount of cracked pepper. Crush the potatoes with a fork or potato masher. Then add a dash of milk and make it into a moderately fine mash.  Force it through a sieve to remove the last of the lumps.

Serving:
(I'd recommend you put boiled peas with it)
Put out a small pile of sweet potato mash, the chicken on top then surround it with peas before putting the mushroom sauce over the top of it all.