Don't toss those kale stems. Chop, place in a heavy plastic bag, and freeze. Add the pieces to your next batch of vegetable soup.
Rub kale with 1 Tbsp. lemon juice and 1/4 tsp. salt in a large bowl until tender and slightly wilted, about 1 minute. Whisk buttermilk, 1 Tbsp. oil, 6 Tbsp. cheese, Worcestershire sauce, 1 garlic clove, 1/2 tsp. pepper, and remaining 1 Tbsp. lemon juice in a medium bowl until well combined.
Place a rack 6 inches from heating element; preheat broiler. Lightly oil a small baking sheet. Line a large baking sheet with foil; oil foil. Mix panko, rosemary, remaining 1 Tbsp. cheese, remaining garlic clove, and 1/4 tsp. pepper in a shallow bowl. Put egg in another shallow bowl. Dip halved artichokes one at a time in egg, then panko; transfer to small baking sheet. Brush chicken and onion slices with remaining 1 Tbsp. oil; season with salt and pepper. Arrange in a single layer on lined baking sheet.
Broil chicken and onion until onion is golden and tender and chicken is cooked through, about 5 minutes for onion and 8 to 10 minutes for chicken. Transfer to a cutting board and let chicken rest. Broil artichokes, turning, until golden brown and crisp, about 6 minutes.
Slice chicken. Toss kale with half of dressing and top with chicken, onion, and artichokes. Drizzle with remaining dressing, sprinkle with pepper and serve.