All-Butter Herb Crust

1. In the bowl of a food processor, add your flour, sugar, salt, garlic clove, lemon zest and thyme and pulse for a few seconds until combines and garlic clove is broken up.
2. Add in your cut pieces of cold butter and pulse a few times.
3. Add in 4-6 Tbsp of ice cold water (I add ice to my measuring cup I scoop out of)
4. Pulse a few more times, add additional water until a crumbly but slightly cohesive dough comes together when pinched together between fingers.
5. Dump your pie dough in your 11" tart pan and begin pressing into place. I like to use a tart press or a measuring cup to create an even layer of dough along the bottom and then press my fingers along the edges.
6. Continue pressing into place until you have an even bottom and edges that go along the sides.
7. Place in fridge for at least 30 minutes.
8. Preheat oven to 425 degrees.
9. After 30 minutes, place tart pan on sheet pan (important so it doesn't leak in your oven) and prick with a few holes using a fork. Bake your shell for 20 minutes until it pre-bakes (you will roast mushrooms at the same time). Remove and let cool, drop temperature to 375 degrees.

Tart Filling

1. Place your mushroom in a single layer on a sheet pan and coat with 4 Tbsp of olive oil (or more, you want them coated). Mix until all pieces are coated in olive oil then season with kosher salt. Dot the top of the mushrooms with 2 Tbsp unsalted butter and roast for 15-20 minutes at 425 degrees. Set aside. (roast at same time as pre-baking tart crust)
2. In a large skillet, add your additional 2 Tbsp of olive oil and heat on medium-high. Add your sliced onions and begin cooking stirring consistently. Allow the onions to soften and become translucent and slightly browned. Process should take 10-12 minutes, set aside.
3. In a large measuring cup or bowl whisk together your heavy cream, eggs, parsley, 1/2 tsp kosher salt and several grinds of black pepper.
4. Begin assembling your tart.
5. Place your caramelized onions on the bottom of your cooled tart shell, then add your shredded Parmesan cheese, next pour your heavy cream mixture and finally top with your roasted mushrooms, pressing them in slightly and add some additional thyme leaves.
6. Cover your tart pan with foil and set back on baking sheet. Bake for 25 minutes at 375 degrees. After 25 minutes, remove the foil and bake for another 25 minutes until the center is set and top is golden brown. Top with additional thyme or greens.
7. Allow tart to cool to warm or room temperature. Slice and enjoy!