In a cast iron skillet, heat 1Tbs vegetable oil over medium high heat. When hot and starting to smoke, add in ground beef and 1 tsp kosher salt.
Break up meat with a spoon and continue to cook over medium heat for 15 minutes, stirring occasionally to allow for even browning.
When beef is done cooking, remove from pan and strain off all the excess fat.
While beef cooks, add 1 Tbs of oil to another pan. Add onions and begin to caramelize over medium heat, stirring occasionally and until golden brown, about 15 minutes.
Add mushrooms and cook for 5 minutes.
Add kale and saute until wilted, about 3-4 minutes. Season with 1 tsp of salt, 1/4 tsp black pepper and tarragon.
Set vegetables aside in a bowl.
Toss shaved zucchini with 1 Tbs of oil and season with 1/4 tsp of kosher salt. Add to hot pan and cook until slightly golden and tender, about 3 minutes. Add half of the zucchini into other vegetables and reserve the other half in a separate bowl.
In a blender, add eggs, milk, cream, 2 tsp kosher salt and 1/4 tsp ground black pepper. Blend for one minute.
In a 12 inch cast iron skillet, add 1/2 of ground beef and vegetable mix. Pour 1/2 of quiche base over top and add half of goat cheese on top. Repeat with remaining ground beef and vegetables.
Pour the remaining quiche base on top. Add remaining goat cheese and finish by arranging reserved sliced zucchini on top.
Bake for 1 1/2 hours in 325º oven until top is golden brown and filling is set all the way through. Let rest for 20 minutes before serving.
CHEF'S TIP: Quiche can be made a day ahead and reheated in a 325º oven for 10-15 minutes.Serve with a garden salad with shaved radish for a Mother’s Day brunch.