Caramelized Onion and Mushroom Galette with a Rosemary Crust

In an unsurprising turn of events, it’s been a while since I’ve posted. Finals, end of the semester….very busy times. But I’m back home for Christmas break, with few better things to do than to cook. A lot. First on the list of things to share: my Christmas dinner creation. I’m from a family of meat-eaters, so Christmas dinner in my house means prime rib. I wanted to make something just as special for myself, and I think this galette was the perfect fit. It was also my biggest culinary feat to date (I basically made up the recipe on the fly), which means sharing this recipe is essentially the same as offering my firstborn child. Or something like that. It’s not a quick recipe – but plenty of those to come – but if you have some spare time over the holidays, it’s worth it. Even my dad, the proud owner of a steak-aging fridge, was impressed with the flavor complexity. But, as is often the case with involved dishes, I learned a lot in the process of creating this galette.

First: in the wise words of Chris Morocco, pie dough smells fear. This galette, with it’s rosemary-rich pie pastry, is no exception. When combining the ingredients, be careful to not overwork the pastry. You’ll end up with a tough and chewy final product, far from the flaky buttery beauty that is the end goal. Give it a few quick kneads to form a ball, but don’t go beyond that. When you’re rolling it out, don’t let the dough boss you around. Err on the side of flaky at the beginning (you can always add more moisture if needed). For me, it helped to warm it in my hands just slightly before rolling it out. You want it to be thin, but not unstable. And the beauty of a galette? It doesn’t need to be a perfect circle. Aim for round-ish, but round may be a compromise with the dough. That’s okay.

I toyed with the idea of lots of fillings, but nothing had quite the appeal of caramelized onions and mushrooms. There’s a great balance of sweetness and umami, with a bit of balsamic vinegar to add to the complexity and brighten everything up. Make sure to taste the filling before you add it to the galette, because the addition of the cream can cause you to lose some of the complexity. A touch of salt will even everything out, but you have to know it’s missing in order to know to add it.

And now, the moment we’ve been waiting for, the recipe:

Serves: 8 | Prep time: 1 hr | Total time: 3 hrs


For the pastry:

  • 2 cups all-purpose flour
  • 1/2 tsp salt
  • 1 tsp sugar
  • 3/4 cup COLD butter (I use Earth Balance)
  • 5-8 tbsp water
  • 1/2 tsp rosemary, more to taste

For the filling:

  • 1 onion, sliced
  • 1/2 cup finely chopped mushrooms
  • 1 tsp high-quality balsamic vinegar, more to taste
  • 1/2 cup vegetable broth
  • 1 tbsp vegan sour cream
  • 2-4 tbsp all-purpose flour
  • 5 tbsp olive oil, halved
  • 1 tsp cornstarch
  • 1/2 cup mozzarella shreds (I use daiya)
  • Salt and pepper, to taste


  1. Add oil to heavy-bottomed pot over medium-low heat. Add onion, season with salt, and stir until coated with oil. Let cook for 30-45 minutes or until golden brown
  2. Meanwhile, combine salt, sugar, and rosemary in a large mixing bowl, and sift in the flour. Stir until combined. Cut in butter until the mixture resembles sand-like granules. Add water, starting with 5 tbsp. If the mixture is still dry, add water tbsp by tbsp until it just holds a ball shape. Cover and refrigerate 1 hr.
  3. Once onions are just golden brown, stir in mushrooms until well combined. Season with salt. Add balsamic vinegar and incorporate completely. Let cook until mushrooms have released their moisture and balsamic vinegar has reduced, about 10 minutes. Remove from heat and set aside to cool.
  4. In a small bowl, combine broth and sour cream. Stir in onion mixture and mozzarella shreds, and add flour and cornstarch to mixture as necessary until it slightly thickens (you’re not looking for something that holds its shape, but you don’t want something to viscous. Aim for a middle ground). Season with salt and pepper to taste.
  5. Pre-heat oven to 350. Roll out pastry onto lightly floured surface and transfer to a parchment-lined baking sheet. Add filling to the center, taking care to not pile too high. Focus on the solids, and leave any extra liquid behind in the bowl.
  6. Trim away excess pastry, leaving about 4-5 inches between the filling and the edge. Fold pastry over the filling, pleating every few inches.
  7. Brush pastry with olive oil and bake 40 minutes or until golden brown. Top with flaky sea salt. Let cool 10 minutes and serve!

2 thoughts on “Caramelized Onion and Mushroom Galette with a Rosemary Crust

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