Starchy potatoes are best for mashed potatoes as they tend to result in a fluffier final product. Take care not to over work the potatoes which can cause them to become gluey.
Place the potatoes in a saucepan along with enough cool water to cover and 1/2 tsp. of the salt. Cover and bring to a boil, then reduce to a simmer and cook until fork tender, 15 minutes. Drain potatoes and return to the saucepan over low heat.
In a small pan, combine the cream and butter and warm until butter is melted.
Add cream and butter to potatoes, add remaining 3/4 tsp. salt and pepper, and mash until fluffy. Adjust salt and serve.
Used russet potatoes (unpeeled). Roasted a whole head of peeled garlic cloves in 1 Tbsp. olive oil and the butter while the potatoes boiled. Added the garlic mixture along with cream to potatoes before beating with a hand mixer. Had to adjust the salt a couple times (started with only 1/2 tsp. - ended with about 3/4 tsp.). Because of this, ended up beating the potatoes more than I should have, causing them to become slightly gluey. Very good though.
This works just as well with sweet potatoes, again made with a head of roasted garlic.