Gather and prepare ingredients. Preheat oven to 350F.
Bring a large pot of water to a boil. Cook pasta nests per instructions, about 1 minute. Remove from water and drain, set aside.
Heat 1 TBSP butter in a large sauté pan on medium/high heat. Cook ham until brown on all sides. Remove from pan.
Add 3 TBSP butter to the same pan. Sauté mushrooms, shallot and garlic in butter for about 5 minutes. Deglaze with white wine and reduce heat and cook for about 3 minutes.
Add the flour and mix until flour is completely combined and well mixed. Add the broth and stir to combine, the sauce should begin to thicken.
Add the shredded cheddar, cream cheese and half the parmesan cheese. Reduce heat to low and allow sauce to thicken.
Once the sauce is thickened, add the ham and peas. Fold in the spaghetti. If the sauce is too thick you can add a little water to make it thinner, a few tablespoons at a time.
Once all evenly combined, pour the entire mixture into a greased 9x13” baking dish.
Melt remaining 1 TBSP of butter and mix with the ½ Cup breadcrumbs and remaining ½ Cup parmesan cheese. Sprinkle the breadcrumb mixture over the top.
Bake the dish in the oven 10-15 minutes until the sauce is bubbly and breadcrumbs on top are toasty brown. Remove from oven and allow to rest about 5 minutes before serving.
To plate, scoop about 1 Cup portions from the dish and top with additional cheese & parsley if desired.