Fill a saucepan with 500ml water, the
milk, a good pinch of salt and a grinding
of black pepper, then bring to the boil.
Add the turnips and potatoes and cook
for 2 mins. Strain, drain well and pat dry.
Heat oven to 180C/160C fan/gas 4.
Butter a baking dish and rub the sides
with garlic to just add a hint of flavour.
Mix the cream and mustard in a large
bowl, add the potatoes and turnip, mix
until well coated and season really well.
Layer into the baking dish, flattening the
top level. Can be assembled and chilled
a day ahead.
Bake for 30-40 mins or until
golden brown and the turnip and potato
are cooked through – check with the
point of a sharp knife.