Preheat oven to 450 degrees.
Place bread into food processor, pulse 10 times or until coarse crumbs form to measure ½ cup.
Cook pasta in boiling water 7 minutes, omitting salt and fat in water. Add asparagus, cook 1 minute.
Drain.
Lightly spoon flour into a dry measuring cup and level with a knife.
Place flour, thyme, salt and pepper into medium bowl.
Gradually add milk and broth, stirring with a whisk until well blended.
Melt butter in a medium saucepan over medium-high heat.
Add the onion, sauté 4 minutes.
Add milk mixture, cook until thick (about 4 minutes), stirring constantly.
Remove from heat and stir in lemon juice.
Combine pasta mixture, milk mixture, ham and parsley in a large bowl, spoon into a 2-quart casserole dish.
Sprinkle with bread crumbs and cheese.
Bake at 450 degrees for 10 minutes or until filling is bubbly and topping is golden.
