Heat the chicken broth and the butter in a medium saucepan. (Use a pan with a tight-fitting lid.) When the broth boils, add the raisins and the couscous. Take the saucepan off the heat. Stir the couscous and place the lid on the pan. Let stand.
Heat a large nonstick skillet over medium-high heat. Add the EVOO, 2 turns of the pan. Add the chicken in a single layer, season with salt and pepper, and cook, turning occasionally, until browned all over, 3 to 4 minutes.
While the chicken works, trim the tough tops and root ends from the leeks. Cut the remaining white and tender green parts in half lengthwise, then cut the leeks into 1-inch half-moons. Place the leeks in a colander and run cold water over them. Separate the layers to release the dirt and grit. Rinse the leeks well, then drain.
Stir the leeks into the chicken and wilt for 2 to 3 minutes. Add the wine and let it cook down by half, 3 to 4 minutes. The leeks should be tender, with some bright green color, and the chicken should be cooked through.
Fluff the couscous with a fork and stir in the parsley. Spoon a bed of couscous onto dinner plates and top with the chicken and leeks.