Melt butter in a large skillet or grill pan over medium heat. Once melted, add corn kernels and let sit 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 browned. Remove corn to a separate bowl. Gently wipe and keep skillet/grill pan out for later use.
In a medium bowl, toss chicken with chili powder, dried parsley, garlic powder, paprika, cumin, and salt to coat well.
Heat a skillet/grill pan to medium heat and add olive oil. Add chicken to skillet and cook until chicken is fully cooked, 3-4 minutes. Remove from heat.
Lay a tortilla on a flat surface and top with about 1/4 cup grilled corn, 1/4 of the chicken, 4-5 slices of avocado, a scoop of feta sauce, and chopped parsley. Fold the sides and ends of the tortilla over the filling and roll up.
Once again wipe out the skillet/grill pan used for the chicken. Place burritos seam-side down in pan over medium heat and cook for about 2-3 minutes until lightly browned. Flip and cook on the other side for another 2 minutes. Serve burritos with additional feta sauce.