Preheat the oven to 400°F (205°C).
Season both sides of the chicken thighs with salt and black pepper. Roast in the oven for 30 minutes or until fully cooked and fat is rendered.
Dice onion, celery, carrots, and fennel. Press garlic cloves.
Melt butter in a large pot, add diced vegetables, garlic, salt, and sweat for 6-8 minutes.
Stir in all-purpose flour to create a roux. Add wine and cook for about 30 seconds.
Add chicken broth, heavy cream, thyme, bay leaves, and poultry seasoning. Stir well.
Chop the roasted chicken thighs into small pieces and add to the pot along with frozen peas. Simmer on low for 5 minutes.
Mix the dry dumpling ingredients: all-purpose flour, salt, baking powder, black pepper. Stream in melted butter and milk until just barely combined.
Taste the chicken gravy mixture for seasoning and adjust if needed.
Drop dumplings into the pot.
Cover with a lid and cook for 15 minutes or until the dumplings have expanded and cooked through.
Test a dumpling for doneness by cutting into it; it should be fluffy and cooked through.
