Ham and Potato Gratin for a Crowd (Granny's)

• 10 pounds potatoes boiled
• 1 x salt
• 8 cups garlic sauce with mustard
• 5 ounces butter
• 1 cup flour, all-purpose
• 6 1/2 cups milk hot
• 1 x salt
• 1 x black pepper
• 1 pinch nutmeg
• 2 large garlic cloves pureed
• 1/4 cup dijon mustard
• 1/2 teaspoon thyme or sage
• 4 cups swiss cheese or a mixture of cheese, coarsely grated
• 1 1/2 to 2 quarts ham cooked

1. SPECIAL EQUIPMENT SUGGESTED: A food processor is useful for slicing and grating; and 8-quart covered kettle.
2. A heavy-bottomed 3-quart saucepan, for the sauce.
3. A buttered 6-quart baking dish about 3 inches deep, for the final dish.
4. THE POTATOES: Have ready the kettle containing 4 cups of cold water.
5. Peel the potatoes and slice them 1/4 inch thick, dropping them into the cold water to cover as you do so.
6. Cover the kettle, and bring to the boil.
7. Uncover and boil slowly for 3 to 4 minutes, until barely cooked through eat several slices to check.
8. Drain, cover the kettle again for 3 to 4 minutes to firm up the potato slices, then uncover.
9. THE GARLIC AND MUSTARD SAUCE: Make the classic white sauce; cook the butter and flour together in the saucepan until they foam and froth for 2 minutes without coloring.
10. Off heat pour in half the hot milk; whisk vigorously to blend as you pour in the rest; simmer for 3 minutes, stirring.
11. Remove from heat and whisk in the seasonings; bring to the simmer again; taste carefully, and add additional seasonings to taste.
12. ASSEMBLING: Spoon a 1/16-inch layer of sauce on the bottom of the buttered baking dish.
13. Set aside 3 cups of the sauce and 1 cup of the cheese for the topping.
14. Now, to arrange everything in 4 layers, start with a quart of the potatoes, then a quarter of the ham, follow by a third of the sauce and sprinkle on a third of the cheese.
15. Continue in layers, finishing the final layer with the remaining potatoes and ham; spread on the reserved 3 cups of sauce to cover completely, then the last of the cheese.
16. AHEAD OF TIME NOTE: May be prepared a day in advance, cover when cool and refrigerate.
17. An hour or so before you plan to serve, preheat the oven to 375F (190C).
18. Bake in the upper third level just until the potatoes are bubbling hot and the top has browned nicely.
19. About 45 minutes.
20. AHEAD OF TIME NOTE: May be kept warm uncovered on a hot tray but be sure not to overheat or the potatoes and ham will dry out.

potatoes, salt, garlic sauce, butter, flour, milk, salt, black pepper, nutmeg, garlic, dijon mustard, thyme, swiss cheese, ham cooked

Taken from recipeland.com/recipe/v/ham-potato-gratin-for-crowd-gra-40841 (may not work)