Cook penne according to package instructions, drain, rinse with cold water and reserve.
Heat oven to 400°F.
While the pasta is cooking, heat a large, heavy pan over medium-high heat.
Add the olive oil and ham, and cook until slightly browned, remove from pan and reserve.
Add the mushrooms and cook until just tender, then add the garlic and onions and cook until translucent.
Deglaze the pan with the wine, add the heavy cream and bring to a boil.
Remove the pan from the heat and add the sour cream, peas, tarragon, and pasta and stir to combine.
Combine the parmesan, breadcrumbs, and butter.
Transfer the pasta to a deep baking dish, top with the breadcrumb mixture and bake for 25 minutes, or until the pasta is bubbly and the breadcrumbs are golden brown.