Preheat the oven and prepare your casserole dish. Slice the mushrooms. Also, bring a large pot of salted water to a boil so that it’s ready and you can cook your spaghetti noodles.
Cook the onions and mushrooms until softened. Add the garlic and white wine and cook until liquid is reduced by half.
Cook the veggies
Melt the remaining butter and sprinkle with flour
A roux is simply a fat (like butter) and flour mixed together and then cooked. Whisk the flour covered mushrooms with the butter until a thick paste is formed.
Finish the roux
Add the chicken broth and the heavy cream. Season with salt, pepper, and fresh thyme.
Make the sauce
Add the turkey, frozen peas, and half of the cheese to the sauce.
Mix it all together
Mix in the spaghetti noodles with the sauce & transfer everything to your prepared casserole dish. Top with the remaining shredded cheddar cheese.
Bake and serve