In a large frying pan over medium heat, warm 3 tablespoons of the olive oil. Add half of the green onions and saute until softened. 3-4 minutes. Add half of the garlic and saute for 1 minute. Add the crabmeat and cook until just heated through, about 1 minute. Add salt and black pepper to taste, two-thirds of the lemon zest and all of the juice, and the cayenne. Transfer to a bowl. Add the ricotta, the 1/4 cup creme fraiche, and the chopped basil. Taste and adjust the seasoning. Mix well, cover and refrigerate for at least 1 hour or up to 24 hours.

Using the pasta sheets and the crab mixture, prepare the ravioli and lay them out on floured baking sheets.

Bring a large pot of water to a boil. Meanwhile, in a large frying pan over medium heat, melt the butter with the remaining 2 tablespoons olive oil. Add the remaining green onions and saute until they begin to soften, 3-4 minutes. Add the remaining garlic and saute for 1 minute, not letting it color. Add the tomatoes and salt and black pepper to taste, and cook just until the tomatoes begin to release their juices, about 5 min. Add the white wine and boil for 1 minute. Reduce the heat to low, add the 1 tablespoon creme fraiche and the remaining lemon zest, and cook the sauce for 1 minute. Taste and adjust the seasoning.

Generously salt the boiling water, add the ravioli, and cook until tender, 30 seconds-3 minutes, depending on the freshness of the pasta (unless you have a huge pot, you will probably need to do this in 2 batches). Using a skimmer, transfer to paper towels to drain briefly. Put the ravioli in a warmed large, shallow bowl. Pour the sauce over the ravioli and scatter shredded basil on top. Serve immediately.