Step 1

Preheat the oven to 375°F and place a tray on the bottom rack. Boil at least 2 cups of water. Prepare a round pan by spraying it with non-stick spray or greasing it with 1 tbsp butter. I love to use a springform pan for crustless quiches!

Step 2

Over medium to low heat, melt the butter and saute the 1 red onion until translucent and fragrant. Season them with a pinch of salt. The slower you saute, the sweeter they will become.

Step 3

While the onions cook, add everything else, except the 1 cup button mushroom, to a blender and blend till smooth.

Step 4

Place the mushrooms and caramelized onions in your prepared circular pan or springform, and then pour the egg mixture over them. Stir as needed to distribute the ingredients evenly. Bake for 40-45 minutes, then let cool for at least another 20 before slicing. It’ll continue to set up.