Then, over medium-high heat, boil the potatoes until they are fork tender (10-15 minutes).

After that, drain them, and transfer them to a large mixing bowl.

Last, add the milk, butter, salt, and pepper. Mash them until they are your desired consistency. Set them aside.

First, in a large saucepan or 7-quart dutch oven, over medium heat, combine the ground beef, lamb, onion, salt, pepper, onion powder, garlic powder, paprika, and thyme.

Next, saute the ingredients for 10-15 minutes (while stirring), or until the meat is browned. Add the Worcestershire Sauce and stir to mix.

Now, melt your butter in your microwave or on the stove top, and whisk in the flour to create a simple thickening agent. 

Afterwards, add the butter/flour mixture to the meat and veggies while stirring. Pour in the broth and continue mixing the filling for another 2 minutes. Turn off the heat for assembly.

First, grab a 9x13-inch baking dish or just use the dutch oven and start topping the filling with the mashed potatoes using a spatula or spoon.

Next, smooth out the topping or leave it rustic. Just make sure the pie is totally covered with mashed potatoes.

Then, place the dish in your preheated oven (425 degrees F.) and let it bake for 25 to 35 minutes. 

Last, remove the finished shepherd's pie from the oven and let it cool for about 20 minutes before serving. Top with chives or sliced green onions and serve.