Bring a large pot of lightly salted water to a boil. Cook the pasta in boiling water until cooked through yet firm to the bite, about 11 minutes; drain.
While the pasta cooks, heat the olive oil in a skillet over medium heat. Cook the garlic and red pepper flakes in the hot oil briefly, about 1 minutes. Stir the broccolini into the garlic; cook and stir together for 5 minutes.
Add the fava beans and sun-dried tomatoes and cook until the beans are completely warmed, 3 to 4 minutes.
Remove from heat and toss with the drained pasta in a large bowl.