Add olive oil to a saucepan over medium heat and saute the shallots and salt until translucent. Add in the white wine and simmer over medium high heat until almost no liquid remains, about 5 minutes. Add in the pomegranate juice and continue to reduce until there is only about ⅓ cup liquid - about 15 minutes. Once the sauce is reduced, strain out the shallots if desired (this will give you a nice smooth sauce). This step can be done up to 3 days in advance - store covered in the refrigerator.
While the sauce is reducing, prepare the scallops by removing the tough side muscle on each and patting them very dry. It's very important that the scallops are as dry as possible before cooking in order to achieve a nice sear. Season them with salt and pepper to taste.
When ready to serve, bring the pomegranate reduction back up to temperature in a medium sauce pan and set aside. Preheat the remaining 2 tablespoons olive oil a large non stick pan over medium high heat. When the oil starts to shimmer and almost smoke, carefully place the scallops in the pan, being very careful not to overcrowd (you may have to do them in batches).
Let them sear for about two minutes without touching them, then gently lift one up to see the color. It should be golden and caramelized. If it's not, put it back and crank up the heat. When the scallops are nicely seared, turn them over to the other side and cook for another minute and no more. You want them to be slightly underdone in the center, as they become tough when cooked too much. Remove the scallops to drain on a paper towel.
Remove the pomegranate reduction from the heat. While whisking vigorously, slowly add the butter a few pieces at a time until its all incorporated. Taste for seasoning and adjust as needed.
To serve, place the scallops over a dollop of squash puree then drizzle the beurre blanc around. Garnish with fried leeks and pomegranate seeds if desired. Serve immediately.