Given the task definition and input, reply with output. In this task, you have to generate the named entities (NER) given its ingredients of the recipe. Named entities are the names of the items without their quantity.

2 tsp butter, 1 tsp olive oil, 1 medium onion, finely chopped, 1 pkg (16 oz) frozen spinach, thawed and squeezed dry, 1 1/4 cups heavy cream, 3/4 cup milk, 1 1/3 lbs sweet potatoes, peeled and thinly sliced, 1 1/3 lbs potatoes, peeled and thinly sliced, 1/3 cup grated Parmesan cheese
butter, olive oil, onion, frozen spinach, heavy cream, milk, sweet potatoes, potatoes, Parmesan cheese