Step 1

Preheat oven to 375F. Peel potatoes. Using a mandoline or food processor, slice the potatoes very thin.

Step 2

In a large mixing bowl, whisk together 1/2 cup cream and flour, until there are no lumps. Continue whisking in the remaining cream and milk. Add salt.

Step 3

Place potatoes, onions, and cream mixture in a large heavy saucepan. Turn on heat to medium-high, and cook, stirring gently and occasionally, for about 5 minutes, until mixture comes to a simmer.

Step 4

Stir in ham. Pour mixture into a large casserole dish. Bake for about 50 minutes, until top begins to brown. Remove from oven and cool for a few minutes before serving.