Save I threw this together on a gray Sunday afternoon when unexpected guests called to say they were twenty minutes away. The house smelled like butter and onions within minutes, and by the time they arrived, the tart was cooling on the counter, looking like I'd planned it all week. That's the magic of caramelized onions: they make everything feel intentional, even when you're improvising.
The first time I made this for a picnic, I wrapped it in parchment and carried it in a basket, slicing it on a blanket under the trees. Someone said it tasted like something from a French market, and I didn't correct them. It's become my go-to whenever I want to feel like I've put in more effort than I actually have.
Ingredients
- Puff pastry: The store-bought kind works beautifully here and saves you time, though homemade shortcrust brings a more tender, crumbly texture if you're feeling ambitious.
- Yellow onions: They caramelize into deep golden sweetness, so don't rush this step or substitute with red onions, which turn too soft and lose their structure.
- Butter and olive oil: The combo prevents burning while adding richness, and the butter gives the onions a glossy finish that looks almost lacquered.
- Sugar: Just a teaspoon coaxes out the natural sugars in the onions and speeds up the caramelization without making things cloying.
- Thyme: Fresh is brighter, but dried works in a pinch, and either way it cuts through the richness with a subtle earthiness.
- Goat cheese: The tangy creaminess is non-negotiable here, though feta or even a crumbly blue cheese can step in if you want a sharper bite.
- Eggs, cream, and milk: This custard base binds everything together and bakes into a silky, wobbly center that firms up just enough to slice cleanly.
- Black pepper and salt: Freshly cracked pepper adds little bursts of heat, and salt balances the sweetness so the tart doesn't tip into dessert territory.
Instructions
- Prepare the crust:
- Roll out the pastry into your tart pan, press it gently into the edges, and trim off the overhang with a knife. Prick the base all over with a fork to prevent puffing, then slide it into the fridge while you work on the onions.
- Caramelize the onions:
- Heat the oil in a wide skillet and add the sliced onions, stirring them around until they start to soften and glisten. Toss in the butter, sugar, salt, and thyme, then lower the heat and let them cook slowly, stirring every few minutes, until they turn a deep amber color and taste almost jammy.
- Make the custard:
- Crack the eggs into a bowl and whisk them with the cream, milk, pepper, and salt until smooth and pale. This mixture should be pourable but not too thin.
- Assemble the tart:
- Spread the cooled onions evenly over the chilled pastry, scatter the goat cheese on top, then pour the custard over everything, tilting the pan gently so it fills all the gaps. Don't overfill or it'll spill in the oven.
- Bake until golden:
- Slide the tart into the preheated oven and bake until the custard is just set with a slight wobble in the center and the edges of the pastry are puffed and golden. Let it cool for ten minutes before slicing so the filling firms up and doesn't run.
Save One evening I served this with nothing but a simple green salad and a bottle of cold white wine, and it felt like the kind of meal that makes you forget you're eating at home. My friend scraped her plate and said she'd pay good money for this at a cafe, and I realized sometimes the simplest combinations are the ones that stick with people.
What to Serve Alongside
A handful of bitter greens dressed with lemon and olive oil cuts through the richness beautifully, or you could go with roasted vegetables if you want something heartier. I've also served this with a light soup, like a chilled cucumber or tomato bisque, and it felt elegant without being fussy.
How to Store and Reheat
This tart keeps in the fridge for up to three days, wrapped loosely in foil or tucked into an airtight container. You can eat it cold straight from the fridge, which I do more often than I'd like to admit, or reheat slices in a low oven until just warmed through so the pastry doesn't go soggy.
Ways to Make It Your Own
I've stirred a splash of balsamic vinegar into the onions right at the end for a subtle tang, and it adds a lovely dark glaze. You could also fold in some sauteed mushrooms, swap the goat cheese for something sharper like aged cheddar, or scatter toasted walnuts over the top before baking for a bit of crunch.
- Try adding a handful of baby spinach or arugula into the onions just before assembling for a pop of green.
- A drizzle of honey over the finished tart brings out the sweetness and makes it feel almost decadent.
- If you're serving this as an appetizer, cut it into small squares and serve it on a platter with toothpicks.
Save This tart has become one of those recipes I reach for when I want to feel like I'm taking care of someone, including myself. It's the kind of dish that makes an ordinary day feel special without asking too much of you.
Recipe FAQs
- → How do I caramelize onions properly?
Cook sliced onions slowly over medium heat with olive oil and butter, stirring occasionally until they turn deep golden and sweet, usually about 25 minutes.
- → Can I use other cheeses instead of goat cheese?
Yes, feta or blue cheese can be swapped for goat cheese to create different savory flavor profiles.
- → What pastry works best for the tart base?
Ready-rolled puff pastry is convenient, but homemade shortcrust pastry also creates a tender, flaky base.
- → Is there a way to add more depth to the onion flavor?
Adding a splash of balsamic vinegar during the last minutes of caramelizing enhances sweetness and complexity.
- → How should I serve the tart?
It’s delicious served warm or at room temperature, paired nicely with a crisp green salad and chilled white wine.