Juicy Lamb & Purple Potato Shepherd's Pie with a Blackberry Demi Glace

The Dr. Seuss-ian purple mashed potato topping you see here consists of extras from the Basque potato tortilla that I made for last week's French Fridays with Dorie.  I first got a bee in my bonnet to make a shepherd's pie because Claudia from What's Cooking? recently made an Italian-style version of the dish, which got my tummy rumbling.  I also just happened to have eight braised lamb shoulder chops sitting around.

But why, you ask, when it's just Poppa Trix and me, would I ever need to make such an obscene amount of lamb all at once?  Why, indeed!

I confess, I have lured you in with the other-worldly glow of these purple potatoes in order to share something with you: I am super excited ... no, beyond excited ... okay, maybe freaking out a little that my photos are accompanying an Epicurious feature about St. Patrick's Day.  As I also cooked all the dishes for the spread - a soup, a side, a dessert, and, as I said, those braised lamb shoulder chops - there were a lot of leftovers at Casa de Trix!  Please go check it out and tell me what you think! (Unless you don't like it, and then I won't be sad if you don't say anything, really I don't mind.)

But back to this shepherd's pie. What makes it really special - aside from those purple potatoes, of course -  is the blackberry demi glace. (I know technically this is more of a reduction than a proper demi glace, but that's what I want to call it. Please don't be upset with me, Chef J!) After braising all those lamb chops, I had a considerable amount of stock left over. So I tossed in a sprig of rosemary and set the stock - still in the roasting pan -  to simmer until it reduced by about 85 - 90 percent. At this point I added a couple spoonfuls of blackberry jam and continued to cook until it melted into my sauce. I tasted for seasoning - salt and pepper - and it was good to go.

Meanwhile, I boiled the purple potatoes with their skins on. Once soft, I peeled them and quickly hit them with a shot of lemon juice - the acid helps them retain their luminous color. To this I added butter, cream, salt, and pepper, and whizzed the whole shebang with my handy immersion blender.

For the actual pie, I used carrots, sauteed onions, garlic, peas, and the lamb, which I shredded off of the bone - and of course that scrumptious blackberry sauce. I plopped this whole mixture into a casserole, topped with the potatoes, and baked at 350 F for about 25 minutes, and finished it off in the broiler to try to brown the top. As it turns out, purple potatoes don't really brown ...

It was a little saucy, juicy, and messy - we had to eat it in soup bowls, after all  - but it was mighty tasty. And if you've skimmed this post (I forgive you) and didn't see it before, please go check out my photos in Epicurious!