Preheat oven to 350 degrees F
Sauté onion in oil and sprinkle with a pinch of salt
When onion is soft, add ground chuck and season with salt and pepper
Cook, stirring and breaking up occasionally until browned
Add taco seasoning and a splash of water
Let cook over low to medium heat until liquid has cooked down, about 10 minutes
Add eggs to a bowl and whisk until smooth
Add cheese and heavy cream to eggs and mix
Put taco meat mixture in an ovenproof dish
Pour egg and cheese mixture over the top and spread evenly
Sprinkle extra cheese on top
Bake at 350 degrees F for 30 minutes
Top with salsa, sour cream and guacamole or desired toppings
Can be made a day ahead
