Get water started in a large pot for the pasta, and preheat oven to 200 degrees (for keeping scallops warm).
Season scallops with salt and pepper: Set a large saute pan over medium-high heat until hot, about 1 minute. Add half the butter, swirling to coat bottom of pan. Continue to heat until butter just begins to turn golden brown.
Add half the scallops, one at a time, flat side down; cook, adjusting heat as necessary to prevent fat from burning, until scallops are well browned, 1 1/2 to 2 minutes; Turn scallops over and cook another minute or two (sides will be firmed up and all but middle third of scallop opaque) Do not over cook!
Repeat cooking process using remaining half of butter and scallops.
Transfer scallops to heatproof plate, drizzle them with lemon juice and place in oven oven with door slightly open.
Return skillet to burner; reduce heat to low.
Add shallot and cook 1 to 2 minutes.
(meanwhile, add pasta to pot of boiling water.)
Increase heat to high; add garlic,and wine; bring to boil, scraping pan bottom with wooden spoon to loosen caramelized bits, until liquid reduces to a glaze, 4 to 5 minutes.
Add cream, salt, and pepper and garlic; bring to boil. Reduce heat; simmer until cream reduces very slightly, about 1 minute longer.
Stir in scallions, and tomatoes.
Drain pasta; pour into large bowl. Add sauce; toss to coat.
Divide pasta among individual serving plates, arranging a portion of scallops around or on top of each.