Bring medium saucepan of lightly salted water to a boil. Once boiling, add elbow macaroni and cook until al dente. Drain and cool.
In the meantime, add butter to a non-stick grill pan or frying pan. Once melted, add corn kernels in and let cook for about 4 minutes before stirring. Let sit for another 4 minutes and stir again. Repeat a couple more times until the corn is nicely charred. Remove corn to a large bowl and let cool a bit.
Once corn is cooled, add tuna, chopped chard, cooled macaroni, onion, jalapeño, cilantro, and cotija cheese to the bowl.
In a separate small bowl, stir together mayonnaise, chili powder, cayenne, and freshly squeezed lime juice.
Pour dressing mixture over corn and toss well to combine. Serve salad in individual bowls and top with additional cheese and cilantro.