Step 1

Preheat the oven to 400 degrees F.

Step 2

Grease an 8x8-inch square baking dish with the extra butter.

Step 3

Peel the onion and slice it into 1/4-inch-thick slices.

Step 4

Arrange the slices in a single layer in the prepared baking dish.

Step 5

Melt 2 tablespoons of the butter and pour it all over the onions, then sprinkle them with the salt.

Step 6

Roast the onions until the bottoms are golden, about 20 minutes.

Step 7

Turn the onion slices over and bake them until golden-brown, about 20 more minutes.

Step 8

Garnish with the chopped parsley and serve.