Have ready a bowl of water and two halved lemons. Squeeze 3 of the halves into the water and reserve one half. As you work, rub the reserved lemon half over the cut surface and immediately put the trimmed artichokes in the lemon water to slow the oxidation.
Pull off the outermost leaves of the artichokes until you get down to the lighter yellow leaves. Then, using a serrated knife cut off the top third or so of the artichokes and trim the very bottom of the stem. Peel the stem, using either a paring knife or a y-peeler to remove the entire tough green exterior. Cut the artichoke in half lengthwise. With a spoon or melon baller, scoop out and discard the hairy choke and thorny inner leaves.
Slice cleaned artichokes and drop them in your bowl of acidulated water. Drain and pat dry. Heat extra virgin olive oil in a large skillet over medium-high heat. Sauté the artichokes until crispy, about 5 minutes. Pour in the vegetable broth, and cook 5-6 more minutes. Add chopped kale, salt and pepper to taste and sauté for another 2 minutes.
In the meantime, cook the Ravioli according to package instructions. Drain the Ravioli reserving ½ cup of the pasta cooking water. Add the pasta to the artichoke - kale mixture adding the pasta water a little at a time to loosen the sauce if desired. Divide among plates, garnish with lemon zest and a turn of freshly ground black pepper and serve.