- Preheat oven to 425°F. Melt butter in large cast-iron skillet over medium heat.
- Add onion to hot skillet and cook, stirring occasionally until tender, about 5 to 8 minutes. Stir in flour and cook until no lumps remain, about 1 minute.
- Whisk in broth and heavy cream and cook, stirring occasionally until sauce thickens, about 5 minutes. Stir in chicken, vegetables, salt and pepper until combined. Remove from heat.
- Top chicken and vegetable mixture with an even layer of tater tots until completely covered. Bake until tater tots are fully cooked, about 20 to 25 minutes. Top with parsley and serve.
Tip: Packaged chopped onions can usually be found in the produce aisle of your local grocer.