This Caramelized Onion and Sweet Potato Tart is a treat for your taste buds! With sweet potatoes and golden onions baked in a flaky crust, it offers a lovely blend of flavors.
Trust me, the smell while it’s baking is enough to make your mouth water! I love having it as a cozy dinner or a fancy snack. Just slice and serve—easy peasy!
Key Ingredients & Substitutions
Sweet Potatoes: These are the star of the dish, providing sweetness and creaminess. If you’re short on sweet potatoes, you can use butternut squash for a similar texture and flavor profile.
Onions: Yellow onions are perfect for caramelizing due to their sweetness. If you want a slightly different taste, try using red onions or shallots; they will still yield a lovely caramelized flavor.
Gruyere Cheese: This cheese adds a rich and nutty flavor. If Gruyere isn’t available, Swiss cheese, Fontina, or even a good quality cheddar can make great substitutes!
Heavy Cream: For a lighter option, use half-and-half or whole milk. You can even try a plant-based milk, like cashew or almond, though the texture will change slightly.
Thyme: Fresh thyme brings a wonderful aroma. If you don’t have it, feel free to use dried thyme (just use about a third of the amount) or try fresh rosemary for a different herbaceous note.
How Do I Get the Perfect Caramelized Onions?
Caramelizing onions may seem tricky, but with patience, you’ll get sweet and golden results! Here’s how to do it:
- Start by heating olive oil and butter in a skillet over medium-low heat. This gentle heat is key.
- Add the sliced onions and sprinkle with salt. The salt helps draw out moisture.
- Cook the onions slowly for about 25-30 minutes, stirring occasionally. Don’t rush this process; the magic happens with time!
- They should be golden brown and sweet-smelling. If they start to stick, lower the heat or add a splash of water.
- Once done, season with a bit of black pepper, set aside, and watch them elevate your tart!
Caramelized Onion and Sweet Potato Tart
Ingredients You’ll Need:
For the Crust:
- 1 1/4 cups (150g) all-purpose flour
- 1/2 teaspoon salt
- 8 tablespoons (115g) cold unsalted butter, cubed
- 3-4 tablespoons ice-cold water
For the Filling:
- 2 medium sweet potatoes, peeled and sliced into 1/4-inch rounds
- 2 large yellow onions, thinly sliced
- 2 tablespoons olive oil
- 1 tablespoon unsalted butter
- 1 teaspoon salt (for onions)
- 1/2 teaspoon black pepper, divided
- 1 teaspoon fresh thyme leaves (plus extra for garnish)
- 3 large eggs
- 1 cup (240ml) heavy cream or half-and-half
- 1/2 cup grated Gruyere or Swiss cheese
- 1/4 cup grated Parmesan cheese
How Much Time Will You Need?
This recipe takes about 30 minutes of prep time and then 35-45 minutes to bake, plus an additional 30 minutes to chill the crust. Overall, you’re looking at about 1.5 hours from start to finish, with some waiting time in between. Perfect for a nice evening meal!
Step-by-Step Instructions:
1. Preparing the Crust:
In a mixing bowl, combine the flour and salt. Use a pastry cutter or your fingers to mix in the cold butter until the mixture looks like coarse crumbs. Then, add ice-cold water one tablespoon at a time until the dough starts to come together. Shape the dough into a disk, wrap it in plastic wrap, and chill in the fridge for at least 30 minutes.
2. Caramelizing the Onions:
In a large skillet over medium-low heat, heat the olive oil and butter. Add the sliced onions and sprinkle with salt, stirring to coat. Cook these slowly, stirring occasionally, for about 25-30 minutes until they become golden brown and sweet. Once done, season with a bit of black pepper and remove from heat.
3. Preparing Sweet Potatoes:
While the onions are cooking, preheat your oven to 375°F (190°C). Peel and slice the sweet potatoes into 1/4-inch rounds. Briefly boil or steam them for about 5 minutes to soften, then drain and set them aside.
4. Assembling the Tart:
Roll out the chilled dough on a floured surface to fit a 9-inch tart pan. Place the dough in the pan, trimming any excess, and prick the bottom with a fork to prevent puffing. Spread the caramelized onions evenly over the crust, then layer the sweet potato slices in a circular pattern on top. Sprinkle fresh thyme leaves over everything.
5. Making the Custard:
In a bowl, whisk together the eggs, heavy cream (or half-and-half), salt, and the remaining black pepper. Stir in the grated Gruyere and Parmesan cheeses, ensuring a nice mix. Pour this custard over the vegetables in the tart.
6. Baking the Tart:
Place the tart on a baking sheet and bake for 35-45 minutes, or until the custard has set and the top is golden brown. If the sweet potatoes begin to brown too quickly, cover them loosely with aluminum foil.
7. Serving the Tart:
Once baked, let the tart cool slightly before removing it from the tart pan. Garnish with extra fresh thyme if you like. This tart can be served warm or at room temperature—either way, it’s delicious!
Enjoy your beautiful and tasty Caramelized Onion and Sweet Potato Tart!
Can I Use Store-Bought Pie Crust for This Tart?
Absolutely! If you’re short on time, a store-bought pie crust is a great option. Just follow the package instructions for baking, and you can skip the step of making your own crust.
What Other Vegetables Can I Add?
You can easily customize the filling! Consider adding sautéed spinach, roasted bell peppers, or mushrooms for extra flavor and texture. Just remember to adjust the cooking time based on the vegetables you choose!
Can I Prepare This Tart in Advance?
Yes, you can! Prepare the tart completely and store it uncooked in the fridge for up to a day before baking. Bake it just before you plan to serve it for the best flavor and texture!
How Should I Store Leftovers?
Store any leftovers in an airtight container in the fridge for up to 3 days. You can enjoy it cold or reheat it in the oven at 350°F (175°C) for about 15-20 minutes to warm it through.
