Peel and cut potatoes into ½” pieces, place in a saucepan with enough water to cover potatoes and 1 tablespoon kosher salt. Cover and place on high heat and allow to boil.
While potatoes are cooking, place a large skillet over medium high heat with olive oil in it. Add chicken and stir. Grate onion and add to pan. Stir to combine. Using a garlic press, mince garlic and add to pan. Add 1 teaspoon salt and ½ teaspoon pepper, stir to combine.
Preheat oven to broil.
Meanwhile, in a small saucepan over medium heat whisk 2 Tbsp butter and flour and allow to cook for 3 minutes. Add chicken broth and poultry seasoning. Whisk to combine and cook for 2-3 minutes until thickened.
Add corn and beans to chicken mixture, pour gravy on top. Stir to combine.
Drain potatoes, add 2 Tbsp butter, cream cheese, sour cream, ¼ cup milk, 1 teaspoon kosher salt and ½ teaspoon fresh ground pepper to pan and pour potatoes on top. Mash and combine with potato masher. Add ½ of cheese, stir to combine.
Spread mashed potatoes over top of the chicken mixture. Spread evenly to edges of pan. Sprinkle remaining cheese over top. Place pan in oven under broiler until cheese is golden brown and bubbly. 1-3 minutes. Keep a close eye on cheese.
Remove from oven, sprinkle with parsley, serve and enjoy.