Upside Down Potato and Onion Skillet Tart

Upside Down Potato and Onion Skillet Tart

I use small red potatoes.  I don't peel potatoes as a rule, you can if you prefer.  I just wash them thoroughly and then slice.

2 1/2 tablespoons butter

12 sprigs thyme, strip the leaves from the stems

1 large onion, sliced somewhat thickly ( a tad more than 1/4 inch thick)

1 lb. waxy red potatoes, washed and very thinly sliced
 
2 tablespoons olive oil

1/2 cup grated gruyère

1/2 cup crumbled feta

1 cup grated mozzarella

sea salt and cracked black pepper

Preheat oven to 400°. Melt the butter in a 9-10 inch ovenproof frying pan (cast iron is great) over medium heat. Add the thyme and onion and cook for 5 minutes. Place the potato, oil, cheeses, salt and pepper in a bowl and toss to combine.

Top the onion with the potato mixture and bake for 45 minutes or until golden brown and cooked through. Turn upside down to serve.