This recipe was based off Asparagus Gruyere Tart by Demelza, which my family fell in love with after I adopted her in the PAC game. Since we love mushrooms and onions I decided to create a tart with her basic recipe idea as a starting point.
- Preheat oven to 450 degrees F.
- Line a cookie sheet with a sheet of bakers parchment paper.
- Place a sheet of puffed pastry flat on parchment.
- In skillet over medium low heat add olive oil and butter.
- Saute onion for 15 minutes or until translucent. Stir frequently.
- Add mushrooms to skillet .
- Saute until tender about 15 minutes. Stir frequently.
- Add salt and pepper to mushroom onion mixture (to taste).
- Remove from heat and set aside.
- Mix egg and milk together with a whisk until well blended.
- Paint the puffed pastry with the honey mustard leaving a 1/2 inch border.
- Add the mushroom onion mixture on top of the mustard leaving about a 1/2 inch border.
- Sprinkle the cheese on top of the mushroom onion mixture.
- Paint the border of the puffed pastry dough with egg wash (Discard leftover egg wash).
- Place tart in oven and bake for 15-20 minutes until pastry has puffed up and browned.