Place ricotta, parmesan, butter, salt and pepper in a large bowl. set aside. Fry bacon in skillet til crisp. Transfer bacon to paper plate to drain, crumbling once cooled. Reserve pan and bacon grease.
To the bacon pan, add onion and cook about 3 minutes. Add garlic and cook 1 more minute. Transfer onion mixture to cheese mixture.
Meanwhile, cook pasta in boiling water. When it is just 1 minute till done, add peas to water.
Reserving 1 cup of pasta/pea water, drain pasta and peas. Add half of the pasta water to the cheese mixture along with the lemon juice and mix till smooth.
Add pasta and peas to the cheese mixture and toss to coat, adding more reserved water as necessary to moisten pasta. Stir in bacon bits, adjust seasoning, and serve.