First, the master instructions for making any quiche without a crust:

Omit crust, put everything in a buttered pie pan, and cook at 350 rather than 375 until puffy and brown (in the neighborhood of 25 to 35 mins). I've tried both temps, and I might actually prefer 375 - it gets done faster and I want my darn quiche! YMMV.

OK. That said...

 4 slices of bacon.
 1 TB EVOO
 12 oz of your fave mushrooms (white,cremini, shiitake or mix) sliced thin
 1/2 cups finely chopped onion
 1 TB flat-leafed parsley, finely chopped
 1 gollick clove, minced
 3 large eggs
 1 cup heavy cream (you know you want it!)
 2 teaspoons mustard out of a jar
 3/4 cup of Gruyere, grated

 1) Pre-heat da oven (duh)
 2) Pre-butter your pie plate
 3) Cook the bacon in a large skillet until semi-crisp, drain on paper towels.
 4) Discard all but 1 TB of the bacon fat from the pan.  Add 1 TB
 EVOO. Add the mushrooms and onion and cook, stirring, until the
 mushrooms are lightly browned and the onion is tender, about 5 mins.
 5) Add parsley and garlic and cook for 1 minute more.
 6) Remove from heat, season with salt and pepper to taste.
 7) Snip bacon into 1/4-inch pieces and add to mushroom mixture.
 8) Dump same in pie plate, spreading as evenly as possible.
 9) In a large bowl, whisk eggs until light.  Stir in cream and mustard.
 10) Sprinkle cheese over mushroom mix, then pour in cream mixture.
 11) bake
 12) eat

 Notes: you can substitute half-and-half or light cream if you're so
 inclined.  I actually do "snip" the bacon with a kitchen shears,
 which is easier and quicker than using a knife.  If you like things
 more bacony, you can ignore the EVOO instruction and just use two TB
 of bacon fat.  And making explicit what's implicit in step 4, you
 have to cook the mushrooms at medium high and get them to give up
 their water before they will brown around the edges.  In my
 experience, this will take > 5 minutes, but just go for the goal,
 not the timing.  If the mushrooms retain too much water, you will
 end up with a slightly watery (but still delicious) quiche.

 Other than that, pretty straightforward.

 From Marie Simmons' "The Good Egg."  She has won both a James Beard
 award and a Julia Child Award, and it's full of great egg recipes,
 although I believe OP.