Heat oil in large skillet over medium high heat. Add lamb, garlic, onion powder, Italian seasoning, ground black pepper, and salt. Cook and stir until meat is browned.
Stir in the tomatoes, zucchini, and celery. Cook over medium heat for 10 minutes, stirring occasionally.
Mashed Cauliflower Topping
Steam cauliflower over boiling water in a covered pot for 8 to 10 minutes. Or cook for 2 minutes in an Instant Pot on high pressure then do a quick pressure release.
Transfer cauliflower to a food processor. Add in the cream cheese, cheddar cheese, and heavy cream. Process until mixture is smooth. Alternatively, a hand masher or electric mixer can be used to mash everything together.
Spread the mashed cauliflower mixture over the cooked meat mixture.
Bake in a preheated 350°F oven for 20 to 25 minutes or until topping starts to brown.
In addition to zucchini and celery, any of the following can be added into the meat mixture:
Cut green beans of asparagus
You can also use different ground meat or a blend of meat. If you don’t care for lamb, make a cottage pie instead with ground beef, ground turkey, or ground chicken. And if you want to up the flavor and fat of the meat, toss in some bacon pieces.