This is a traditional recipe from Puglia in southern Italy is originaly called "orecchiette con le cimi di rape". Called broccoli rabe in English, rapini are now commonly found in most North American super markets. Orecchiette is a typical pasta shape for this dish, but you can use any short pasta here. Farfale or cavatelli are good alternatives.
Cut rapini in small pieces of about an inch, discarding the hollow end of the stem and the bigger, thicker leafs. Set aside. Bring a large pot of water to a boil and salt it heavily; it should taste like seawater. Add the orecchiette and cook until al dente. Use this time to heat the olive oil in a small saucepan set over low heat with the garlic and hot peppers. Two to three minutes before the orecchiette are ready, add rapini to water stirring often. Once cooked, drain the pasta and rapini and set aside in a large serving bowl. Add hot oil, garlic and hot pepper. Toss to combine everything. Add pepper and parmigiano to taste. You can drizzle a little high-quality olive oil over the dish right when you serve, too.
Make sure you cook the garlic at low heat to avoid burning it and to get a soft texture that will amalgamate better with the pasta once you toss all the ingredients together.
Drain heavily, as water left in the pasta might dilute the taste of the dish.
You can blend part of the cooked rapini together with a bit of cooking water to get a creamier texture.
Some add chopped sausage or panceta to this dish.
You can substitute rapini with broccoli.