Colcannon Shepherd's Pie

INGREDIENTS

1 tsp

extra-virgin olive oil

1 1/2 lb

ground lamb

Kosher salt and freshly ground pepper

medium onion, chopped (2 cups)

carrots, peeled and cut into 1/4-inch coins (1 1/4 cups)

3 tbsp

tomato paste

1 tbsp

unbleached all-purpose flour

1 tbsp

Worcestershire sauce

1 3/4 cups

low-sodium chicken broth

1 cup

frozen peas

3/4 cup

packed chopped flat-leaf parsley

2 1/2 lb

Yukon Gold potatoes, peeled and cut into 1 1/2-inch pieces

Kosher salt and freshly ground pepper

1 tbsp

extra-virgin olive oil

1 lb

Savoy cabbage, thinly sliced (5 cups)

2/3 cup

whole milk, warmed

4 tbsp

unsalted butter, melted, plus more for brushing