Preheat oven to 425 F.
Melt some cooking fat in a skillet or oven-proof pan over medium-high heat.
Cooking fat
Add the garlic, carrots, red onion, and celery to the skillet, and cook for 3 to 4 minutes.
3 to 4 carrots, 1 cup red onion, 2 garlic cloves, 1 celery stalk
Add mushrooms and cook another 3 to 4 minutes.
1 cup cremini mushrooms
Poor in the white wine, if using, and continue cooking until reduced by half, making sure to scrape the bottom of the pan.
¼ cup white wine
Stir in the chicken stock, fresh dill, and shredded chicken, and cook another 5 minutes.
2 cups chicken stock, 1 tbsp. fresh dill, 4 cups pre-cooked chicken
Place skillet in the oven and bake for 15 minutes.