Heat the oven to 350 F (180 C) and lightly grease a 3-quart baking dish.

Cook the penne pasta in boiling salted water following the package directions for al dente. Drain and set aside.

Meanwhile, make the sauce. Melt 4 tablespoons of butter in a large skillet over medium heat. Add the mushrooms and shallots with a dash of salt and pepper. Cook for 6 to 8 minutes or until the mushrooms are browned and the liquids have evaporated. Add the garlic and cook for 1 minute longer.

Sprinkle flour over the mushroom mixture and cook, stirring constantly, for 2 minutes. Gradually add the milk and continue cooking until thickened. Add the cheese , ham, and peas and cook until the cheese is melted. Taste for seasoning and add salt and pepper, to taste.

Combine the sauce mixture with the drained pasta and turn into the prepared baking dish.

Melt the remaining 3 tablespoons of butter and toss with the breadcrumbs to coat; sprinkle over the casserole.

Bake for 25 to 35 minutes or until the topping is browned and the casserole is bubbling around the edges.