Ready in 45 minutes
One 16-ounce container of ricotta is enough for this recipe and leftovers.
Heat oil in large nonstick skillet over medium-high heat. Add onions. Saut? until onions are pale golden, about 5 minutes. Reduce heat to medium; saut? onions until tender and deep golden, about 15 minutes longer. Transfer 3/4 cup saut?ed onions to small bowl. Add peas to onions in skillet. Saut? until peas are crisp-tender, about 3 minutes. Remove skillet from heat.
Cook pasta in large pot of boiling salted water until just tender but still firm to bite. Drain pasta, reserving 1 cup cooking liquid.
Add pasta and 1/2 cup cooking liquid to onion mixture; stir over medium-high heat 30 seconds. Mix in ricotta, basil, and lemon peel, adding more cooking liquid to moisten as needed. Season with salt and pepper.