Ham & Potato Gratin for a Crowd (Granny's)
Submitted by SPOILED
Granny’s ham and potato gratin for a crowd layers parboiled potatoes, diced ham, and Swiss cheese with a mustard-garlic bechamel. Feeds 24, bakes in under an hour, and can be assembled a day ahead.
YIELD
24 servingsPREP
10 minCOOK
50 minREADY
60 minWhen you need to feed a packed table, this gratin is a dinner-party workhorse. Layers of parboiled potatoes, diced ham, and Swiss cheese blanketed in a Dijon-and-garlic bechamel, baked until the top is golden and the edges bubble.
Parboiling the potatoes is the step most home cooks skip and shouldn’t. Sliced raw potatoes in a gratin need a long, slow bake to cook through, which dries out the ham and the sauce. Giving them three or four minutes in boiling water, then letting them steam covered to firm back up, means they bake in 45 minutes instead of 90.
The sauce is a classic bechamel built on a proper blonde roux, cooked at least two minutes to lose the raw flour taste. Whisking half the hot milk in off the heat is the trick that prevents lumps. Finish with a pinch of nutmeg, pureed garlic, and Dijon for the signature flavour.
This is the rare gratin that actually improves when assembled the day before. The flavours settle, and all you do an hour before dinner is slide the dish into a 375°F (190°C) oven.
Pro Tips
- Slice potatoes ¼ inch thick on a mandoline or food processor, uniform slices cook at the same rate.
- Use a heavy-bottomed saucepan for the bechamel, thin pans scorch the milk.
- Reserve cheese and sauce for the top layer, as the recipe directs, it gives you that golden, bubbly crust.
- If the top browns before the centre is hot, tent with foil for the last 15 minutes.
Variations
- Swap Swiss for a mix of gruyere and sharp cheddar for a more assertive, savoury edge.
- Stir sauteed leeks or caramelized onions between the layers for extra sweetness.
- Replace ham with crumbled cooked bacon or shredded rotisserie chicken for a weekday variation.
Ingredients
Directions
SPECIAL EQUIPMENT SUGGESTED: A food processor is useful for slicing and grating; and 8-quart covered kettle.
A heavy-bottomed 3-quart saucepan, for the sauce.
A buttered 6-quart baking dish about 3 inches deep, for the final dish.
THE POTATOES: Have ready the kettle containing 4 cups of cold water.
Peel the potatoes and slice them ¼ inch thick, dropping them into the cold water to cover as you do so.
Cover the kettle, and bring to the boil.
Uncover and boil slowly for 3 to 4 minutes, until barely cooked through eat several slices to check.
Drain, cover the kettle again for 3 to 4 minutes to firm up the potato slices, then uncover.
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.
Off heat pour in half the hot milk; whisk vigorously to blend as you pour in the rest; simmer for 3 minutes, stirring.
Remove from heat and whisk in the seasonings; bring to the simmer again; taste carefully, and add additional seasonings to taste.
ASSEMBLING: Spoon a 1/16-inch layer of sauce on the bottom of the buttered baking dish.
Set aside 3 cups of the sauce and 1 cup of the cheese for the topping.
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.
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.
AHEAD OF TIME NOTE: May be prepared a day in advance, cover when cool and refrigerate.
An hour or so before you plan to serve, preheat the oven to 375℉ (190℃).
Bake in the upper third level just until the potatoes are bubbling hot and the top has browned nicely.
About 45 minutes.
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.
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