Remove the salmon from the refrigerator and let it stand at room temperature for 10 minutes while you prepare the other ingredients. Heat the oven to 375 degrees F. Line a large baking dish or rimmed baking sheet with a piece of aluminum foil large enough to easily wrap all the way around the salmon and seal it. Lightly coat the foil with nonstick spray. With paper towels, lightly pat the salmon dry. Place the salmon in the center.
In a small bowl, stir together the brown sugar, chipotle chile powder, lime zest, and salt. Brush the salmon with the olive oil (or melted butter) and lime juice. Sprinkle with the chipotle seasoning mixture, rubbing if needed to coat the salmon evenly.
Fold the sides of the aluminum foil up and over the top of the salmon until it is completely enclosed. If your piece of foil is not large enough, place a second piece on top and fold the edges under so that it forms a sealed packet. Leave a little room inside the foil for air to circulate.
Bake the salmon for 12 to 18 minutes, until the salmon is almost completely cooked through at the thickest part. The cooking time will vary based on the thickness of your salmon. If your side is thinner (around 1 inch thick) check early to ensure your salmon does not overcook. If your piece is very thick (1 1/2 inches or more), it may need longer.
Remove the salmon from the oven and carefully open the foil so that the top of the fish is completely uncovered (be careful of hot steam). Change the oven setting to broil, then return the fish to the oven and broil for 3 minutes, until the top of the salmon is slightly golden and the fish is cooked through. Watch the salmon closely as it broils to make sure it doesn’t overcook. Remove the salmon from the oven. If it still appears a bit underdone, you can wrap the foil back over the top and let it rest for a few minutes. Do not let it sit too long—salmon can progress from not done to overdone very quickly. As soon as it flakes easily with a fork, it's ready. Alternatively, you can check the salmon's temperature with an an instant-read thermometer. At 145 degrees F, it is done.
To serve, cut the salmon into portions. Sprinkle with fresh cilantro or top with an extra squeeze of lime juice as desired.