Turkey Pie with Yam Potatoes and Beans

This is a fabulous and healthier alternative to the tradional version of hamburger and potatoes.
1 lb yams, peeled and cut into chunks
1 cup milk
½ tsp. sea salt
¼ tsp. black pepper, freshly ground
1 lb lean ground turkey breast
1 medium onion, chopped
3 cloves garlic, minced
¼ tsp. dried thyme
1½ cups frozen peas and carrots
1 cup navy beans, rinsed and drained
2 Tbsp. hi-maize resistant starch
1 Tbsp. cornstarch
2 tsp. Dijon mustard
1 tsp. Worcestershire sauce
Preheat the oven to 350°F (180°C/160°C fan, Gas Mark 4). Coat a 6-cup baking dish with cooking spray.
Combine the yams in a medium saucepan with enough cold water to cover by 2". Bring to a boil over medium-high heat and cook for 10 minutes, or until tender. Drain and return the potatoes to the pan. Add ¼ cup of the milk, ¼ tsp. of the salt, and 1/8 tsp. of the pepper and mash. Reserve.
Meanwhile, coat a large non-stick skillet with cooking spray and heat over medium-high heat. Add the turkey and cook, breaking it into smaller pieces with a wooden spoon, for 4-5 minutes, or until no longer pink. Mix in the onion, garlic, and thyme and cook, stirring occasionally, for 4-5 minutes, or until the turkey starts to brown and the onion begins to soften. Add the peas and carrots and beans and cook for 1 minute.
Remove from the heat and stir in the remaining ¾ cup milk, the resistant starch, cornstarch, mustard, Worcestershire sauce, and the remaining ¼ tsp. salt and 1/8 tsp. pepper.
Pour the mixture into the prepared baking dish. Spread the top with the mashed yams to cover. Bake for 20-25 minutes, or until the filling is bubbly and the top is slightly browned.
Cool for 10 minutes before serving.