Place a medium-size skillet over medium high heat with the butter and 2 turns of the pan of EVOO, about 2 tablespoons. Once the butter has melted and the skillet is hot, add the onion, salt and freshly ground black pepper and cook, stirring frequently for 2-3 minutes, until the onions start to get tender. Add the pimiento, sprinkle the onions with the flour, stir to combine and cook for 1 minute. Add the wine, and whisk in the stock and cream. Season the mixture with some salt, pepper, nutmeg and hot sauce to taste. Bring up to a bubble, add the scallops and simmer for 1 minute.
Fold the scallop mixture into the smashed-up potatoes. Taste and re-season with salt and pepper.
Pile the mixture into the potato boats and top with the Gruyere cheese. Pop into the oven to melt and brown the cheese. Before serving, garnish with the chopped chives.