1. Bring a medium pot of salted water to a boil over high heat. Add the beans and cook for 1 minute. Remove the beans with a slotted spoon and transfer them to a bowl of ice water. Once cool, drain the beans and set them aside on a kitchen towel.
2. Grease a 9 × 13-inch casserole dish or other dish 2 to 3 inches deep and around 3 1/2 quarts, with 1 tablespoon of the softened butter. Lay the beans in the dish in an even layer and set aside.
3. Grease the sides and bottom of a rimmed baking sheet (jelly- roll pan) with 1 tablespoon of the remaining softened butter. Cut two pieces of parchment paper the size of the pan and use another tablespoon of the remaining softened butter to grease the papers. Line the pan with one of the pieces of parchment, buttered side up. Reserve the other.
4. Whisk the eggs in a medium bowl and set aside. Combine
the grated cheeses in a second small bowl and set aside.
5. Add 4 cups of the milk, 4 tablespoons (1/2 stick) of the butter, 1 1/2 teaspoons of the salt, and the pepper to a 3- quart or larger heavy- bottomed saucepan and heat over medium- high heat until the liquid begins to bubble. Using a whisk, gradually add the semolina while stirring vigorously. Reduce the heat to medium- low and continue to cook, stirring with a rubber spatula or wooden spoon, for 10 minutes. The mixture will become very thick. Stir in the blue cheese and half the grated cheese mixture and remove from the heat.
6. Add 1/2 cup of the semolina mixture to the eggs and whisk
to combine. Add another 1/2 cup and whisk in, then whisk in
1/2 cup more. Return the semolina mixture to the pot and stir until thoroughly combined. Transfer the mixture to the prepared baking sheet and, using a rubber spatula (an offset metal icing spatula works very well too), spread it evenly in the pan. (Since the gnocchi won’t be pourable, this will take a little effort.) Lay the buttered side of the reserved parchment on top of the gnocchi. Set another jelly- roll pan on top and weight it with a few cans. Refrigerate until completely cool, at least 30 minutes (this can be done up to 1 day ahead).
7. Preheat the oven to 450°F.
8. While the semolina is cooling, melt the remaining 4 tablespoons (1/2 stick) butter in a small pot over medium- high heat. Add the onion, celery, garlic, and remaining 1/2 teaspoon salt and cook, stirring as needed, until the vegetables are soft, about 5 minutes. Add the ham and cook for 2 minutes. Sprinkle in the all-purpose flour, stir to combine, and cook for 1 minute longer. Whisk in the stock and the remaining 1/2 cup milk and cook, stirring, until no floury taste remains, about 5 minutes. Remove from the heat.
9. Pour the ham mixture over the green beans and spread in
an even layer.
10. Remove the semolina from the refrigerator. Remove the
top jelly-roll pan and the top piece of parchment. Invert the gnocchi onto a cutting surface and peel off the last piece of parchment. Using a 1 1/2- to 2- inch round cutter, cut the semolina into circles. Lay the circles in rows on top of the ham mixture, overlapping them like shingles to cover the ham mixture completely. Dot the top with the remaining 2 tablespoons of softened butter and sprinkle the remaining grated cheeses over the top. Bake for 20 minutes, until bubbly and nicely browned. Serve immediately.
Yield: 6 to 8 servings
Note: At the point when it’s ready to bake, the casserole can be covered and refrigerated for up to 2 days. The baking
time may increase slightly.