Creamy baked Potato and Celeriac

This is unctuous, creamy and divine!


4 tablespoons butter, melted, plus a couple extra knobs, divided
2 pounds potatoes, peeled
1 small celeriac, peeled and halved
Sea salt and freshly ground black pepper
1 pint heavy cream
1 clove garlic, peeled and finely chopped
1/2 a small bunch fresh sage, leaves picked and roughly chopped
4 ounces freshly grated Parmesan, divided
Preheat the oven to 350 degrees F and butter a large, shallow baking dish.

Slice the potatoes and celeriac into disks just under 1-inch thick.

Place the slices into a large pan, cover with cold water, season with salt and pepper and bring to the boil.
Simmer for 5 minutes, then drain in a colander and allow the vegetables to steam dry for a minute or so. Put back into the pan with the cream, chopped garlic, sage, half the Parmesan and a good pinch of salt and pepper.
Mix together, then tip into the buttered baking dish and spread out evenly. Pour any mixture left in the pan over the top.
Sprinkle over the remaining Parmesan, cover tightly with aluminum foil and cook in the preheated oven for 35 to 40 minutes until golden brown.

When the potatoes are cooked, take them out of the oven, remove the foil and sprinkle over the remaining Parmesan. Return the dish to the oven, uncovered, and bake for another 10 to 15 minutes until bubbling and golden.