This Savory Onion Tart is everything you want in a cozy, rustic dish: buttery crust, sweet caramelized onions, creamy filling, and just a hint of cheese and herbs to tie it all together. It’s easy to make with store-bought or homemade pastry and feels fancy enough for brunch, dinner parties, or holiday tables.
But here’s the secret: kids usually love it too! The onions turn sweet and mild after cooking, and the flaky crust is basically irresistible. It’s delicious warm, at room temp, or cold from the fridge with a side salad.
🛒 What You’ll Need
For the Tart Crust (or use store-bought):
- 1¼ cups all-purpose flour
- ½ teaspoon salt
- ½ cup (1 stick) cold butter, cubed
- 3–4 tablespoons ice water
For the Filling:
- 2 tablespoons olive oil or butter
- 4 large yellow onions, thinly sliced
- 1 teaspoon sugar
- Salt and pepper, to taste
- 2 large eggs
- ½ cup heavy cream or half & half
- ½ cup grated Gruyère or Swiss cheese (optional)
- Fresh thyme or chives, for garnish
👩🍳 Pro Tips for Tart Success
- Slice onions evenly so they caramelize at the same rate.
- Low and slow is key for caramelizing—don’t rush it!
- Chill your dough before baking for the flakiest crust.
- Blind bake the crust so it doesn’t get soggy.
- Make it mini – use muffin tins for individual onion tartlets.
🛠 Tools You’ll Need
- Tart pan (9-inch round)
- Rolling pin
- Skillet
- Whisk
- Mixing bowls
- Baking weights or dried beans (for blind baking)
🔄 Substitutions & Variations
- Gluten-free crust – Use a GF pastry mix or almond flour-based crust
- Vegan version – Use vegan butter, dairy-free cream, and flax eggs
- Add-ins – Bacon bits, goat cheese, or sautéed mushrooms
- No Gruyère? Use sharp cheddar, parmesan, or skip cheese altogether
⏰ Make Ahead Tips
- Caramelize onions up to 3 days ahead and refrigerate
- Make dough ahead and store in fridge for 2 days or freeze
- Fully bake tart and reheat before serving—great for brunch prep
👩🍳 How to Make a Savory Onion Tart
1. Make the Crust
In a bowl, mix flour and salt, then cut in cold butter until crumbly. Add ice water 1 tbsp at a time, mixing until dough holds together. Shape into a disc, wrap, and chill for 30 minutes.
2. Roll & Blind Bake the Crust
Roll out chilled dough and press into tart pan. Trim edges. Prick with a fork, line with parchment, and fill with baking weights. Bake at 375°F (190°C) for 15 minutes, remove weights, then bake 5 more minutes.
3. Caramelize the Onions
In a skillet, heat olive oil over medium-low. Add sliced onions, a pinch of salt, and sugar. Cook slowly, stirring often, until golden and sweet—about 25–30 minutes.
4. Make the Filling
In a bowl, whisk together eggs, cream, salt, and pepper. Stir in cheese (if using).
5. Assemble & Bake
Layer caramelized onions into the crust, then pour the egg mixture over. Bake at 375°F for 25–30 minutes, or until filling is set and slightly golden.
6. Cool, Slice & Garnish
Let the tart cool slightly before slicing. Garnish with fresh thyme or chives and serve warm or at room temp.
🧊 Leftovers & Storage
- Fridge: Store covered in the fridge for up to 3 days
- Reheat in oven or toaster oven for 10 minutes at 350°F
- Freezer-friendly: Freeze slices individually and reheat from frozen
🥧 Time to Slice into Something Special!
This Savory Onion Tart is one of those simple-but-special recipes that always impresses. The buttery crust, sweet onions, and creamy filling make a perfect combo that works for brunch, lunch, or even a light dinner with a salad.
Tried it? Let me know in the comments! Did you add cheese, herbs, or maybe some bacon? I’d love to hear how you made it your own! 💬🧅🥧
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