Peel and cube the sweet potatoes, cover with cold salted water and bring to a boil over high heat. Simmer over medium heat until very tender, about 15 minutes. Drain and mash with the milk and half the salt.
Dice the onion and carrots and chop the mushrooms.
Heat a large deep skillet over medium-high heat. Add the turkey, onion, carrots and mushrooms and cook, breaking up the meat, until it reaches 74°C (165°F), about 8 minutes.
Stir in the tomato paste for 1 minute, then add the broth, Worcestershire sauce, thyme and the rest of the salt. Mix the cornstarch with 2 tbsp of cold water, stir it in and simmer over medium heat for 3 minutes until thick. Stir in the peas.
Preheat the oven to 200°C (400°F) with a rack in the centre.
Spread the filling in a 23 x 33 cm (9 x 13 inch) baking dish and top with the sweet potato mash, spreading to the edges.
Bake for 20 minutes, until bubbling at the edges and lightly browned on top.
Rest for 10 minutes so the filling sets before spooning onto plates.
Made it? Rate it
Your rating helps other lifters pick their next meal.