1. Season the chicken with salt and pepper. Heat oil in a skillet over medium-high heat and sear the chicken until golden and cooked through to 165°F. Transfer to a plate and keep warm.

2. Reduce heat to medium and melt 2 tablespoon of butter in the same skillet. Add minced garlic and cook for about 1 minute until fragrant but not browned.

3. Sprinkle flour over garlic and stir to form a paste. Cook for 1-2 minutes, stirring constantly. Gradually whisk in chicken broth, smoothing out lumps. Let gravy simmer until thickened. Stir in heavy cream if using, and season with salt and pepper to taste.

4. Meanwhile, bring a pot of salted water to a boil. Add cubed Yukon Gold potatoes and cook until fork-tender, about 12-15 minutes. Drain well.

5. Mash hot, drained potatoes with 2 tablespoon of butter and warm milk until smooth and creamy. Stir in shredded cheddar cheese until melted. Season with salt and pepper to taste.

6. If desired, slice seared chicken. Spoon cheesy mashed potatoes onto each plate, top with chicken, and ladle warm garlic gravy over everything. Garnish with chopped parsley or chives.