1 lb. linguine
12 oz. bacon, cut crosswise into ½” slices
1 very large onion, halved, sliced (about 6 cups)
2 large bunches Swiss chard, stemmed, chopped (about 12 cups)
1 tbsp. balsamic vinegar
3 tbsps. extra-virgin olive oil
6 cloves garlic, pressed
¼ tsp. celery salt
pepper
²⁄₃ cup grated Parmesan cheese

Cook linguine in large pot of boiling salted water until tender but still firm to bite, stirring occasionally. Drain, reserving 1 cup pasta cooking liquid.

Meanwhile, cook bacon in heavy large pot over medium heat until beginning to crisp, about 10 mins. Transfer to paper towels to drain. Drain all but 2 tbsps. bacon drippings from skillet. Add onion and saute over medium-high heat until softened, about 7 mins. Add Swiss chard and garlic and sprinkle with salt and pepper. Add pasta cooking liquid to skillet. Toss until chard is wilted and tender, about 4 mins. Sprinkle vinegar over; cook 1 min.