I had some leeks that were looking tired. I always have mushrooms and tomatoes to hand. And some kind of cheese. And it was late of an evening so dinner needed to spring pretty much full-formed from the fridge. Sort of like Athena from Zeus's head. —boulangere
Preheat oven to 375 degrees. Spray a baking casserole's sides and bottom with pan spray.
Heat a skillet over medium-high heat. Add olive oil. When it shimmers, add leeks along with a dusting of good sea or kosher salt. Stir now and then, and as they begin to soften, add sliced mushrooms along with another good dash of salt to hasten release of their water. When their juices begin to thicken in the bottom of the skillet, add tomatoes, and as their juices begin to collect, remove from heat.
In a mixing bowl whisk together eggs and cream. Stir in chunks of Brie, then stir in buttery soft leeks, mushrooms, and tomatoes. Add a dash of salt and some fresh ground pepper. Turn into your prepared casserole dish. Place in oven and bake for 30 minutes, rotating at the 15-minute point. Fritatta is done when you can bounce a finger off the top and it feels springy with a bit of tenderness lingering. It shouldn't feel rubbery. Remove from oven, cover with your prettiest kitchen towel, and let sit for 10 minutes before serving.