Quiche with caramelized onions, mushrooms, and Gruyere on an oatmeal crust

Ingredients:

Cake

• 3/4 cup rolled oats
• 0.5 cups premium flour
• 1/4 teaspoon salt
• 3 tablespoons chilled, unsalted butter, cut into small pieces
• 3 tbsp. chilled low-fat sour milk (or kefir)

Filling

• 4 tsp olive oil
• 1 large onion, sliced ​​into thin half rings
• 220 g of chopped various mushrooms, such as button mushrooms, oyster mushrooms, and shiitake mushrooms
• 0.5 tsp salt
• 1/4 tsp ground black pepper
• 1/4 tsp mustard powder
• 1 tbsp chopped fresh thyme leaves (or 1 tsp dried)
• 3 large eggs
• 3 egg whites
• 1 cup of unsweetened low-fat condensed milk
• 2/3 cup grated Gruyere (about 30 g)

Preparation:

1. Preheat oven to 200°C. Spray a 9-inch pie pan with cooking spray.
2. Cake:
   In the bowl of a food processor, combine the oats, flour, and salt and pulse 3 times. Add the butter and pulse about 12 times, until crumbly. Add the buttermilk and pulse 3-5 more times to combine. Form the mixture into a ball and place it between two large pieces of waxed paper. Roll the dough into a circle about 25 cm in diameter.
3. Remove the top sheet of wax paper. Invert the dough, still on the other piece of paper, into the pie dish, then peel off the wax paper. Gently press the dough into the dish. Bake for 9 minutes and let cool.
4. Filling:
   In a large nonstick skillet, heat 2 teaspoons olive oil over medium-low heat. Add the onion and cook, stirring occasionally, until golden brown and caramelized, about 20 minutes. Transfer the onion to a bowl. Add the remaining 2 teaspoons olive oil to the skillet and heat over medium-high heat. Add the mushrooms and cook, stirring occasionally, until they release their juices and begin to brown, about 6 minutes. Return the onion to the skillet, season with salt and pepper, mustard, and thyme.
5. In a medium bowl, whisk together eggs, egg whites, and unsweetened condensed milk.
6. Sprinkle the cheese over the crust. Top with the mushroom mixture and pour the egg mixture over it. Reduce the oven temperature to 350°F (175°C). Bake for 35 minutes or until a knife inserted into the center of the quiche comes out clean. Let rest for 5 minutes, then cut the quiche into 6 pieces and serve.
   
   
   Excellent source: protein, riboflavin, phosphorus, selenium.
   
   Good source: vitamin A, niacin, vitamin D, pantothenic acid, calcium, iodine, iron, potassium