Place Butter In A Glass 9-In. Pie Plate; Place In A 400 Degrees F Oven For 2-3 Minutes Or Until Butter Is Melted. Remove From The Oven. In A Bowl, Whisk Milk, Flour, Eggs And Salt Until Smooth; Pour Into Hot Pie Plate. Bake At 400 Degrees F For 25 Minutes Or Until Puffed And Golden. Meanwhile, In A Skillet, Saute Mushrooms And Onion In Butter Until Tender; Remove And Set Aside. In The Same Skillet, Cook Sausage Over Medium Heat Until No Longer Pink; Drain. Stir In Broccoli And Rice Are Tender. Stir In Mushroom Mixture And Cheese. Cover And Keep Warm When Pancake Is Removed From Oven, Immediately Spoon Filling Into Center And Serve.