Melt butter in a large stockpot over medium-high heat. Add onion, celery, black pepper, salt, and mushrooms; sauté 4 minutes or until mushrooms are tender. Add sherry; cook 1 minute.
Gradually add flour to pan; cook 3 minutes, stirring constantly (mixture will be thick) with a whisk. Gradually add chicken bouillon cubes and water, stirring constantly. Bring to a boil. Reduce heat; simmer 5 minutes, stirring frequently. Remove from heat.
Add 1 3/4 cups Parmesan cheese and cream cheese, stirring with a whisk until cream cheese melts. Add pasta, chicken broccoli and almonds; stir until blended. Coat 9 x 11 glass or ceramic baking dishes cooking spray and pour in dish.
Place bread in food processor; pulse 10 times or until coarse crumbs form. Combine breadcrumbs and ½ cup Parmesan cheese; sprinkle evenly over pasta.
Bake at 350° for 30 minutes or until lightly browned and bubbly. Remove casserole from oven; let stand 15 minutes.