Combine the potatoes and 1 teaspoon of the salt in a large saucepan
over medium heat. Cover the potatoes with water and cook until fork-tender, about 20 minutes. Drain
Return the potatoes to the pan and, over low heat, stir them with a fork or wire whisk
for about 1 minute to dehydrate
them. Add the cream, butter, garlic, and spinach
. Stir to mix well. Add the remaining 1/2 teaspoon salt and the white pepper
. Mix well. Serve immediately.