In a large pot of boiling, salted water, cook potatoes until fork tender. Drain & pour back into hot pot. Add cream cheese, butter, milk & salt & mash well until potatoes are fluffy. Cover pot & keep potatoes warm.

Meanwhile, while potatoes are cooking, in a large skillet heat oil over medium heat. Add onion, celery & carrot & cook, stirring, until vegetables begin to soften. Crumble ground turkey over vegetables & cook until meat loses it's pink color.

Sprinkle flour over cooked turkey & stir to combine. Dissolve turkey base in the boiling water & stir into meat. Simmer, stirring, about five minutes, until mixture thickens slightly.

Pour meat filling into a 2-3 quart casserole & sprinkle peas over. Carefully spread warm mashed potatoes over filling, sealing potatoes to edge of dish.

Bake in preheated 350 degree oven for 30 minutes, until heated through & bubbly at edge of dish. Remove from oven & sprinkle cheese on top. Bake an additional 5 minutes, just until cheese melts.