Fill a large pot with water, add salt, and bring to a boil
Preheat the oven to 350°F (175°C)
Cook the linguine according to the package directions, then drain and set aside
Melt the butter in a large skillet over medium heat
Add the diced onion and garlic and cook for 2 minutes
Whisk in the flour until combined
add the chicken broth and whisk until smooth
Whisk in the heavy cream until smooth
Stir in the mushrooms, turkey, shredded parmesan cheese, and peas, then turn off the heat
Add the drained linguine to the skillet and stir until well coated in the sauce
Sprinkle the top with breadcrumbs and grated parmesan cheese
Bake for 20-25 minutes until golden brown and bubbly
Remove from the oven and let cool slightly before serving