Bring a large pot of lightly salted water to boiling. Add pasta and cook al dente according to package directions. Drain and keep warm.
Meanwhile, for the Swiss chard, remove and slice the stems. Cut leaves in half lengthwise and thinly slice. Set aside.
In a large skillet or Dutch oven cook bacon over medium-high heat for 4 – 5 minutes or until lightly browned. Add onion and cook, stirring, for 2 minutes. Add chard stems and cook 1 minute. Add chard leaves and cook, stirring, for 2 minutes or until wilted.
Add pasta and oil; cook and stir until heated through.