How is Sheperd's Pie This Good?

Tonight I was trying to figure out what to do with some leftover roasted turkey and mashed potatoes. I decided to make my own version of Shepherd's Pie. This will definitely go into my recipe notebook; Dan and I both rated it a 5 star recipe. I think the secret is the mashed potatoes but the seasoning in the gravy really added flavor, too.

Buttermilk Mashed Potatoes

9 Yukon Gold potatoes, peel half of them
1/2 cup buttermilk
1.5 tbsp butter or margarine
2 tbsp light cream cheese (I used the whipped cream cheese from Trader Joe's)
2 tbsp light sour cream
1 tbsp fresh parsley, chopped

In a large pot, cover potatoes with water and bring to a boil. Cook until fork tender (until a fork goes in and comes out of the potatoes easily). Drain potatoes and add back to the hot pot to evaporate any remaining water. Add remaining ingredients (except parsely) to pot and mash to desired consistency. I like my potatoes a bit lumpy and rustic, which is why I only peeled half of the potatoes. Lightly fold in parsley.

1.5 tbsp butter
1.5 tbsp flour
3/4 cup low sodium chicken broth
a pinch of: ground sage, ground thyme, freshly ground black pepper, poultry seasoning, salt
6 oz roasted turkey breast, shredded
1 cup frozen mixed vegetables, defrosted (mine had corn, peas, carrots, and green beans)
1.5 cup mashed potatoes
paprika

Preheat oven to 350 degrees. Melt butter in a pan. Whisk in flour and cook 2 min. Slowly whisk in chicken broth. Start with a couple tablespoons and whisk until completely smooth to avoid lumps. Add a couple tablespoons at a time, whisking until completely smooth in between. Add all seasonings except paprika and cook 5 min, whisking often. Add turkey breast and mixed vegetables and cook until warmed. Spoon turkey mixture into the bottom of a 1.5 quart casserole dish. Spread potatoes on top and sprinkle lightly with paprika. Cook covered 10 min; remove cover and cook an additional 10 min or until bubbly. If potatoes are leftover and come from the refrigerator, increase covered cooking time approximately 10 minutes.