Cheddar Topped Shepherd's Pie

I made this for St. Patrick's Day this year... And was made to promise that I wouldn't wait until next St. Patrick's Day to make it again!

I did make a wee change from the recipe I found in Everyday Food magazine. The directions call for 1 cup of water to be added to the meat mixture. This left the meat bland, in my opinion. Good... OK... But bland. My fix for that? Use 1 cup of Guinness. It adds flavor to the meat. Funny bit of info for you: No one in my house drinks beer. But I keep a bottle of Guinness corked (with a wine cork) and in the fridge for cooking.

The recipe serves 8- or more. But it's really easy to half...

Ingredients
* 2 pounds baking potatoes (about 4), peeled and thinly sliced
* Coarse salt and ground pepper
* 1 tablespoon vegetable oil, such as safflower
* 6 medium carrots, halved lengthwise, quartered if large, and thinly sliced
* 6 celery stalks, thinly sliced
note: you can add practically any veggie to this: green beans, leeks, small florets of broccoli...
* 1 large onion, chopped
* 1/2 teaspoon dried thyme
* 1/4 cup all-purpose flour
* 1/4 cup tomato paste
* 2 pounds ground beef chuck (you could also use ground turkey or a half/half mix of turkey & beef)
* 1 c Guinness (optional)
* 1 cup whole milk (I used skim)
* 1 1/2 cups shredded sharp white cheddar (6 ounces)

Directions
1. Preheat oven to 450. Place potatoes in a large saucepan, and cover by 1 inch with salted water. Bring to a boil; reduce to a simmer. Cook until potatoes are easily pierced with the tip of a paring knife, 15 to 20 minutes.

2. Meanwhile, heat oil in a 5-quart Dutch oven or heavy pot over medium-high. Add carrots, celery, onion, and thyme. Cook, stirring occasionally, until vegetables are tender, 8 to 10 minutes. Add flour and tomato paste; cook, stirring, 1 minute. Add beef; cook, stirring occasionally, until no longer pink, 6 to 8 minutes. Add 1 cup water or Guinness; bring to a boil, and simmer 1 minute. Set beef filling aside.

3. Drain potatoes; return to pan. Cook over medium, stirring, until liquid has evaporated and a thin film covers bottom of pan, about 1 minute. Remove pan from heat; add milk and 1 cup cheese. Mash until smooth; season cheddar-potato topping with salt and pepper.

4. Pour beef filling into a 13-by-9-inch baking dish. Drop dollops of topping over filling; spread to edges with a spatula. Using a fork, make decorative peaks; sprinkle with remaining 1/2 cup cheese. Bake until topping is browned and filling is bubbling rapidly, about 20 minutes (if topping and filling were chilled, increase to 35 minutes). Let stand 5 minutes before serving.

Make Ahead Tip: Both filling and topping can be made up to a day ahead and refrigerated separately.