Cooking grains in a risotto style may seem fairly unhealthy because the texture is so creamy and luxurious. However, with the exception of a tablespoon and a half of butter, this risotto is cream-free. The texture comes from the starch of the grains, which get released slowly over time and create a self-saucing effect.
Add the broth to a small sauce pot over medium heat and bring it to a simmer.
Meanwhile, add the olive oil to a large sauce pan and sauté the onions and garlic until soft and translucent, then add the bulgur and toast it lightly. Add the broth to the bulgur 1 ladle at a time, making sure to stir constantly and let the grains absorb all the liquid before adding the next ladleful. While the risotto is cooking, toss the Swiss chard into a colander and set it over the simmering broth until it starts to wilt and the stalks begin to soften, then set it aside.
When all of the broth has been used and the consistency of the risotto is rich and creamy stir in salt and pepper to taste, followed by the butter and lemon zest. Fold the chard into the risotto and let it all cook together for a final minute.
Serve the risotto immediately, topped with grated Parmesan cheese.