Heat broth in saucepan and keep warm while preparing remaining ingredients.
Heat oil in large sauté pan Add sausage, sauté until browned, 10-12 minutes per side. Transfer sausage to paper towel lined plate. When cooled, slice into 1/2 inch rounds and set aside.
In the sausage pan sauté fennel and onion until they begin to soften and brown (about 5 minutes). Add garlic, pepper flakes and thyme and cook stirring constantly for 2 minutes. Transfer vegetables to a bowl.
Add orzo to the sauté pan, stirring to coat pasta with residual oil in the pan; cook 2 minutes.
Deglaze pan with wine. Add 1 1/2 warm broth to orzo; cook stirring constantly until broth is nearly absorbed; another 5 minutes. Add remaining 1 cup broth; cook and stir until liquid is fully absorbed.
Stir in sausage slices, vegetable mixture, then add parmesan, butter, parsley, lemon zest and chopped fennel fronds. Season with salt and pepper.
Saute onions and garlic in olive oil. Add salt and pepper. Add sliced yellow squash to pan. Cook slightly. Add petit diced tomatoes. Heat a few minutes. Right before serving, add cream. Heat 1 - 2 minutes (do not boil).
Brown beef in 3 Tbs. butter, add onions and sauté until golden. Mix meat and onions with ketchup and Worcestershire sauce. Season to taste with salt & pepper. Add as little beef stock and cook covered over low heat for 15 to 20 minutes. Beat egg yolks until light, whites until stiff. Beat yolks, cream remaining, 1/2 cup butter and garlic powder into mashed potatoes. Gently fold in beaten egg whites. Put meat mixture into casserole and top with potatoes, sprinkle with Parmesan cheese and bake at 350 degrees until puffed and browned.