Caramelized Onion, Mixed Mushroom & Gruyere Pie
Submitted by happyzhangbo
Savory vegetarian pie with caramelized onions, mixed mushrooms, and Gruyere in a rustic oat-flour crust. A lighter quiche-style main dish with an earthy, nutty depth of flavor.
YIELD
6 servingsPREP
35 minCOOK
60 minREADY
120 minThis pie has layers of flavor that keep revealing themselves with every forkful.
First, the crust: a rustic blend of rolled oats, flour, and cold butter pulsed together in a food processor with buttermilk. It bakes up nutty and crumbly, with more character than any standard pie dough.
Then the filling. Onions caramelized low and slow for a full 20 minutes until they’re deeply golden and sweet. Mixed mushrooms (cremini, oyster, shiitake, whatever you’ve got) seared until they release their water and start to brown. Thyme, dry mustard, and freshly ground pepper tying it all together.
Grated Gruyere melts into a custard of eggs, egg whites, and evaporated milk that bakes into a silky, quiche-like center.
Chef Tips
- Caramelize the onions properly. Twenty minutes over medium-low heat, stirring occasionally. Don’t rush it with higher heat or you’ll get burnt spots instead of even, deep sweetness.
- Don’t crowd the mushrooms. They need space to brown, not steam. If your pan isn’t big enough, cook them in two batches.
- Pre-bake the oat crust for 9 minutes before filling. This keeps the bottom from getting soggy under all that custard.
- Let the pie rest a few minutes before cutting. The custard needs a moment to set or it’ll run when you slice.
Ingredients
Directions
Preheat the oven to 400℉ (200℃). Spray a 9-inch pie dish with cooking spray.
For the crust:
Place the oats, flour and salt in the bowl of a food processor and pulse 3 times to combine.
Add the butter and pulse about 14 times, until you get a pebbly course texture. Add the buttermilk and pulse 3 to 5 times more to combine.
Form the mixture into a ball and place it between 2 large pieces of waxed paper. Roll out into a circle about 10 inches in diameter. Remove the top sheet of waxed paper.
Transfer the crust, still on the other piece of waxed paper to the pie dish, then remove the waxed paper from the top. Press the crust gently into the dish. Bake for 9 minutes, then let cool.
For the filling:
Heat 2 teaspoons of oil in a large nonstick pan over a medium-low heat.
Stir in the onion and cook, stirring occasionally, until golden brown and caramelized, about 20 minutes. Transfer the onions to a bowl.
Add the remaining 2 teaspoons of oil to the pan and heat over a medium-high heat.
Add the mushrooms and cook, stirring occasionally, until they have released their water and begin to brown, about 6 minutes.
Add the onions back to the pan, then add the salt, pepper, mustard and thyme.
In a medium bowl whisk together the eggs, egg whites and evaporated milk. Sprinkle the cheese into the pie crust. Top with the mushroom-onion mixture and pour the egg mixture on top.
Reduce oven temperature to 350℉ (180℃). Bake for 35 minutes or until knife or wooden stick inserted in the middle comes out clean. Let stand for 5 a few minutes before serving.
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