In a covered 2-quart saucepan place potatoes and add enough water to cover, heat to boiling on high. Reduce heat to medium; uncover and simmer 18 minutes or until tender.
Drain well: return the potatoes to the saucepan, add milk, cream cheese and 1/4 teaspoon of the salt and 1/4 teaspoon black pepper. Mash until smooth.
Preheat oven to 425 degrees.
Heat large skillet on medium high heat, add beef and 1/4 teaspoon of the salt and 1/4 teaspoon of the black pepper, cook about 5 minutes or until browned and cooked through, stirring and breaking up the meat.
With a slotted spoon, transfer beef to a large bowl.
In the same skillet on medium high heat, add onions, celery, and carrots, add 1/4 teaspoon salt and 1/4 teaspoon black pepper. Cook for about 8 minutes until veggies are soft
Add wine to veggies, cook for about 2 minutes, stirring to incorporate brown bits from the pan and until reduced by half.
Stir in thyme and beef, along with any juices
Add peas and corn and combine well.
10. In a 3-quart baking dish, add beef and veggie mixture and spread evenly.
11. Top with the mashed potatoes and spread to cover the beef and veggies.
12 Bake for 25 minutes until top is golden brown.