Cook pasta according to package directions and keep the pasta liquid
Meanwhile in a large skillet, combine the oil, garlic and chili flakes, and cook over medium heat to lightly toast the garlic, about 3-4 minutes
Add the rapini, and season; toss to combine and increase the heat to medium high heat
Cook to wilt the rapini, about 4-5 minutes, then add the pasta water, beans and cooked pasta
Toss well, allowing the pasta to cook in the sauce for a minute
Add the butter, olive oil and Pecorino Romano and toss well until creamy; add the lemon juice and mix; taste and adjust seasoning and consistency as needed (the sauce should be light and coat the ingredients)
Transfer the pasta to a serving dish and top with freshly grated Pecorino Romano
