Preheat oven to 375 degrees.
In a large saute pan melt the butter and add the sliced leeks.
Saute the leeks on medium heat for 7 minutes or until soft.
Add the mushrooms to the leeks and saute for another 5 minutes or until the mushrooms have let out their liquid. Drain the liquid from the pan.
Meanwhile beat the remaining ingredients, except the cheese, together for 3 minutes.
Stir in the cheese and the leek mixture (be sure NOT to include any liquid in the pan) into the beaten eggs and dairy.
Pour the entire mixture into the prepared cauliflower crust.
Bake for 30-35 minutes or until the top is set and a knife ran into the center comes out clean.
Serve immediately for best results.