Wild Mushroom, Onion, and Potato Tart – Zenwise Wild Mushroom, Onion, and Potato Tart – Zenwise
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Healthy foods

Wild Mushroom, Onion, and Potato Tart

It’s no secret we love store-bought puff pastry. It makes quick work of appetizers, doubles as pie crust, and is a kitchen staple for elegant entertaining…such as this delicious tart!

This tart has a flaky puff pastry crust that gets filled with mashed potatoes, wild mushrooms, and flavorful caramelized onions. Top it off with fresh herbs, bake until the crust is golden brown and the end result is savory, creamy and sweet all at the same time. 

This rustic pie can act as a full meal, side dish or appetizer. Since it can be served hot or at room temperature, it can also act as an impressive hors d‘oeuvre.


Why We Love These Ingredients

Mushrooms are not only packed with immune-boosting compounds, they’re also gut friendly! Mushrooms contain polysaccharides that can pass through stomach acids to stimulate the growth of healthy bacteria in the gut.

Mushrooms can keep cholesterol levels in check. Research shows they block cholesterol from getting absorbed into the bloodstream.  What’s more, mushrooms act as powerful antioxidants that can protect against free radical damage to your cells

The medicinal properties of onions have been recognized for thousands of years. Athletes in ancient Greece supposedly used onions to purify their blood, while medieval and traditional doctors prescribed them to help treat headaches, heart disease, and mouth sores.

The health secret in onions is called quercetin. It’s an antioxidant and anti-inflammatory that supports healthy blood pressure level, boost bone density and promote cardiovascular health.

Thyme is a healing powerhouse! It’s touted for its ability to soothe acne, fight infections, ease coughs, and even improve your mood. Meanwhile, some of the health benefits of tarragon include pain relief, better insulin sensitivity, and stronger immune function.


Pro Tips To Get You Started

Scoring the border of the puff pastry, puffs up the crust as the butter within the pastry layers melt, expanding the layers in the roaring hot oven.  Before you bake, lightly brush the crust with whole milk or buttermilk. This will give the tart a nice golden color.

It’s important that the potatoes are sliced thin, as in less than ¼”.  A mandolin makes easy work of this.

Store any leftovers between layers of parchment, sealed in a container in the refrigerator, for up to 3 days. Reheat slices in a moderate oven or toaster oven for best results.

Let’s get cooking!


Wild Mushroom, Potato and Onion Tart

Prep time: 20 minutes

Cook time: 30 minutes

Servings: 4


  • 1 package prepared puff pastry ,thawed in the refrigerator
  • All-purpose flour, for dusting
  • 12 ounces any fresh wild mushrooms
  • Extra-virgin olive oil
  • Kosher salt
  • 1-2 TBSP Whole milk or buttermilk to brush the crust
  • 1/4 cup Swiss cheese, grated
  • 1/8 cup  Gruyère cheese, grated
  • 1 pound Yukon gold potatoes [about 4 medium potatoes] sliced inch thick on a mandolin
  • ½ to 1 cup sliced onions [about 2 medium onions], caramelized
  • Leaves from 5 to 9 sprigs fresh thyme
  • Freshly ground black pepper and flake salt
  • 3 stems fresh tarragon


  1. Unfold the pastry onto a lightly floured sheet of parchment and roll to a rough rectangle. With a sharp paring knife, hold the knife edge perpendicular to the pastry and score a border 1 inch in from the edge, all the way around. Transfer to a sheet pan and chill in the refrigerator while you prepare the toppings. Preheat the oven to 400°F.

  2. Slice the mushrooms into ¼-inch pieces. In a large cast iron skillet, cook the mushrooms with a drizzle of oil and a pinch of salt until they begin to collapse and brown, 5 to 7 minutes, turning occasionally. Remove the pan from the heat and set aside.

  3. Take the pastry out of the fridge. With a pastry brush, brush the buttermilk onto the border.

  4. Sprinkle the cheese in an even layer onto the pastry, inside the border. Layer the potato slices, then scatter the caramelized onions on top. Sprinkle half the thyme leaves, then add the mushrooms, followed by the remaining thyme leaves. Season with pepper and drizzle a very small amount of oil, just enough to kiss the surface.

  5. Bake the tart on a sheet pan until the pastry is golden and the cheese is melted, 25 to 30 minutes, rotating the pan after 20 minutes. Cool the tart on a wire rack for 5 minutes.

  6. Cut into slices, season with salt and freshly ground pepper and garnish with fresh thyme and tarragon leaves.



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