Mushroom, Caramelized Onion and Potato Tart

This potato tart with goat cheese and thyme is the perfect savory dish to use for any occasion. While called a tart, it can also most definitely be called a pie or galette. Baked in a cast iron skillet rather than a tart pan or pie dish, this recipe can also very simply be made right on a sheet pan.

Rustic and delicious, a flaky all-butter pie crust is filled with mashed potatoes, then sprinkled with goat cheese (or gorgonzola or parmesan), browned mushrooms, and caramelized onions. Top the whole thing off with fresh thyme and bake until the crust is golden brown and perfect.

Upon slicing in, you see the distinct layers of each. The flavors and textures merry perfectly, leaving you going back for one more bite time and time again! It's crunchy, creamy, sharp and sweet all at the same time. Delicious!

Other savory pastry options include: Spinach and Smoked Salmon Quiche, Prosciutto Asparagus Puff Pastry Bundles, and Ham and Swiss Quiche.

• Pie crust. This recipe uses my all-butter pie crust. I highly suggest making this, as it provides the best flavor and texture.
• Mashed potato layer. Potatoes, butter, milk, sour cream, salt and pepper.
• Mushrooms. Standard button mushrooms or any variety of mushroom you'd like.
• Caramelized onions. Made with two large onions - these cook down to almost nothing.

⏱Timing tip! While waiting for the pie dough to hydrate, make the caramelized onions, mushrooms, and mashed potatoes. These can also all be made a day in advance and assembled and baked before serving.

STEP 1: Make the all-butter pie crust and allow it to hydrate in the fridge for 2 hours.

STEP 2: Thinly slice the onions and caramelize over low to medium low heat, stirring occasionally until a deep golden color is formed. This takes about an hour. Transfer to a bowl.

STEP 3: Clean and quarter the mushrooms, then add to a very hot pan with oil and toss to coat. Allow them to sit for one minute, then toss again and sit. Allow the mushrooms to develop a deep golden color. Transfer to a bowl.

STEP 4: Peel and evenly chop the potatoes, then add to boiling water and cook until a sharp knife inserted goes in and out easily. Drain, then add the butter, milk, sour cream and seasonings and mash until smooth. Cool completely.

STEP 5: Roll out the pie dough on a lightly floured surface, then transfer the dough to a cast iron skillet or a sheet pan lined with parchment paper.

STEP 6: To the center of the dough (leaving 2-3" around the edges), spread on the mashed potatoes and top with dollops of goat cheese.

Then, add on the mushrooms, caramelized onions, and fresh thyme leaves.

STEP 7: Fold the pie dough edges towards the center, gently creasing areas as needed. Whisk together an egg with a small splash of water then brush the egg wash onto the exposed dough. Bake in a 375℉/190℃ for 45-55 minutes until the pastry is golden, then cool for about 15 minutes. Slice and serve!

Store the potato and onion tart covered in the fridge for 3-5 days. Reheat the tart or slices in the microwave, or in a 350℉ oven until the mashed potato layer is warm.

This tart should not be frozen.

I would not suggest doing so for this recipe. The all-butter pie crust rolls out to a much larger piece of dough than store bought, which is needed to hold all of the delicious fillings.

Thankfully, this recipe actually doesn't even require a tart pan. You only need a cast iron skillet or large baking pan.

• Spinach and Feta Pinwheels
• Crab Pretzel
• Prosciutto Asparagus Puff Pastry Bundles

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