Bring a large pot of water to a rolling boil and season it generously with salt. Add the farfalle, stir, and boil for 2 minutes short of the package directions (about 9 minutes). Reserve 1 cup of the pasta water, then drain.
To a large pot/wide pan on medium heat, add the butter and olive oil. Once hot, add the onions and saute for 3-4 minutes or until softened and translucent. Then add the garlic and cook for an additional minute. Stir in the corn kernels and cook for 4-5 minutes or until tender.
Pour in the whipping cream, and bring to a simmer. Once slightly thickened, add the parmesan, and season with salt and pepper to taste. Then gently mix in the crab, and warm it through.
Remove from the heat and stir in the lemon zest and juice. Add the pasta, and a bit of the pasta water (anywhere from ¼ cup-¾ cup) to loosen the sauce.
Stir in half the green onions. Pour into a serving dish and garnish with the remaining green onions.
