Season your chicken thighs or breasts generously with salt and black pepper on both sides.

In a large skillet, heat 1 tablespoon of butter over medium-high heat until it begins to sizzle. Carefully add the chicken and sear for 4-5 minutes on each side.

Remove the chicken from the skillet and set it aside.

Add the remaining tablespoon of butter to the skillet, then add the finely chopped yellow onion and sauté for about 5 minutes until soft and golden.

Add minced garlic and cook for an additional minute.

Sprinkle flour over the onion and garlic mixture and stir for about 2 minutes to form a roux.

Gradually whisk in the chicken broth, scraping any browned bits at the bottom, and bring to a simmer.

Return the chicken to the skillet, cover, and let it simmer for 15-20 minutes.

While the chicken simmers, bring a large pot of salted water to a boil. Add the peeled and cubed potatoes and cook for about 15 minutes until fork-tender.

Drain the potatoes, return them to the pot, and add warmed milk or heavy cream and shredded cheddar cheese. Mash until smooth and season with salt and black pepper.

To serve, scoop a generous portion of cheesy mashed potatoes onto each plate, top with the chicken and garlic gravy.

Sprinkle with freshly chopped parsley if desired.