In a mixing bowl, combine the shredded chicken, mayonnaise, Dijon mustard, garlic powder, paprika, salt, and pepper. Mix well until the chicken is evenly coated with the dressing.
In a separate bowl, mash the ripe avocado with a fork until creamy. Season lightly with salt and pepper.
Preheat a skillet or non-stick grill pan over medium heat. Add olive oil to coat the pan.
Slice the whole-grain sandwich rolls in half and spread the mashed avocado evenly on the bottom half of each roll.
On top of the avocado, layer a generous amount of the chicken mixture followed by sprinkling shredded mozzarella cheese over the chicken.
Top with fresh arugula or spinach leaves for a fresh crunch, then place the top half of the roll to close the sandwich.
Carefully place the sandwiches in the heated skillet, pressing down gently. Grill for about 3-4 minutes on each side or until the bread is golden brown and the cheese is melted.
Remove the sandwiches from the skillet and allow them to cool for a minute before slicing in half for easier eating.
Notes
Serve with a side of sweet potato fries or a light salad. Garnish with freshly chopped herbs for a pop of color.