Start preheating the oven to 400 f.

Butter your deep 9 inch pie dish and set it aside.

Boil vegetables according to the package directions, strain well and set aside.

In a large pan, add the meat along with the onion. Season with salt, black pepper, and any spices you prefer. Cook until browned and cooked through. Once the meat is done, strain off any excess fat and set it aside. Skip this step if using leftover meat and not adding onion.

In a large bowl, whisk together the eggs very well, about 30 seconds of vigorous mixing.

Add in the whole milk and mix until well combined. Season with salt and pepper to taste and mix again.

Stir in the cheddar cheese, cooked meat and mixed vegetables, mix.

Pour it into the greased pie dish, spreading the ingredients evenly. 

Place the pie dish in the pre-heated oven on a baking sheet in case it spills over the dish while cooking.

Bake for 35-40 minutes or until golden brown on top and a knife inserted into the center comes out clean. You'll know its ready when the surface is slightly puffed, evenly browned and the edges are browned as well.

Once the quiche is done, remove it from the oven and let it cool for about 10-20 minutes on a wire rack.

Cut into wedges and serve warm, or refrigerate once cooled for a make-ahead meal.