No-fuss Shepherd's Pie

We used beef mince instead of lamb (does that make it a Milkmaid's Pie?), and about 2/3 of a can of tomatoes, as I had run out of tomato concentrate. We also served it as 'Deconstructed Shepherd's Pie' tonight, as I was in a rush and didn't have the time to bake it in the oven - as all ingredients were already cooked through, why not?

The result was delicious, but a little flat - unsurprisingly, if you've read the comments below the recipe. We ate half today and will eat the other half tomorrow, properly baked as it should be, with lots of cheese added, we'll see if that makes a difference.

Edited later on: Yes, it does.

Edited sometime in autumn 2016: Don't make the potato purée according to that recipe - it uses way too much butter! Just make it the way you always make it.