2 teaspoons kosher salt, divided
1 cup packed baby spinach leaves or roughly chopped large spinach leaves
1 stick unsalted butter
2 garlic cloves, thinly sliced
½ teaspoon freshly ground black pepper, divided
8 chicken wings
1 tablespoon all-purpose flour
¼ cup canola oil
2 tablespoons brine-packed capers, rinsed
2 tablespoons finely chopped flat-leaf parsley
2 cups watercress, tough ends removed
1. To a large bowl, add the ice and cover with cold water. Bring a large saucepan of water to a boil over high heat. Add 1 teaspoon of the salt and the spinach and blanch until the spinach is tender and tears easily, about 2 minutes. Use a skimmer or slotted spoon to transfer the spinach to the ice-water bath to cool. Strain the spinach into a fine-mesh sieve, then squeeze as much liquid as possible from the spinach.
2. To a small skillet set over medium heat, add the butter. Melt, swirling the pan occasionally, until the white solids turn golden and the butter smells nutty, 2 to 3 minutes. Stir in the garlic and cook until the garlic turns golden-brown, about 30 seconds.
3. Pour the garlic-browned butter into a blender. Add the spinach and blend on high speed until the mixture is completely smooth, about 1 minute. Add ½ teaspoon of salt and ¼ teaspoon of pepper and blend to combine.
4. To a large bowl, add the chicken wings and the flour and toss to coat. In a large skillet set over medium-high heat, add the oil. Add the chicken wings and cook the wings until the sides in contact with the pan are golden-brown, about 3 minutes. Turn the wings over and brown the other side, 2 to 3 minutes longer. Squeeze the juice from the lemon half over the wings. Season with the remaining ½ teaspoon of salt, the remaining ¼ teaspoon of pepper, the capers and the parsley. Stir to combine. Divide the watercress among 4 plates. Top each with 2 chicken wings, the spinach sauce and some of the lemon-caper pan sauce, and serve.