Have made this for years. Easy recipe that you can use with ground beef or lamb.. I tend to mix as my kids just are not crazy for lamb like ole mom is.. sometimes I just leave out the lamb all together .. everything in 1 even has the veggies in there.
boil potatoes until tender . drain. add milk, salt, pepper, butter, parsley and mash . you want them to be light and fluffy to spread on top.
brown meat in skillet with onion and garlic, do not drain!
add cajun spice, bouillon cubes and mash, Add flour . Stir mixing well
slowly add water to meat mixture over med high heat and cook until thickened . add Worcestershire and mustard. Add frozen veggies and cook for 10 minutes or med low.
once veggies are tender pour mixture into casserole dish . Top with mashed potatoes ( its easier if you pipe them on using a pastry bag but dropping gently on top and spreading will work just be light handed to not push taters down into mixture
bake at 350 for 15 minutes. Top with cheese and cook 15 more minutes. Let rest for 15. Enjoy!