Triple-Threat Onion Galette
Peer reviewed by UK recipe editorsAuthored by UK recipe editorsOriginally published 28 Jan 2026
Meets Patient’s editorial guidelines
- DownloadDownload
- Share
- Language
- Discussion
- Audio Version
This triple onion galette is a celebration of savoury flavours, combining golden caramelised onions, toasted garlic and charred spring onions. The crust uses a clever folding technique to achieve a flaky, puff-pastry-style finish that perfectly complements the rich, cheesy filling. A layer of Dijon mustard adds a sharp, sophisticated depth that cuts through the sweetness of the onions and the saltiness of the Parmesan.
As a versatile vegetarian dish, this galette works beautifully as a late-summer lunch or a comforting midweek supper when paired with a crisp green salad. It is an excellent choice for entertaining, as both the pastry and the onion filling can be prepared ahead of time, leaving you only the assembly and baking to do before your guests arrive.
In this article:
Video picks
Continue reading below
Ingredients for Triple-Threat Onion Galette
1 tablespoon sugar
1 1/2 teaspoons Diamond Crystal or 1 teaspoon Morton kosher salt
190g (188 g) plain flour, plus more for dusting
12 tablespoons (1 1/2 sticks) chilled unsalted butter, cut into (1/2") pieces
4 tablespoons unsalted butter, divided
1 large onion, thinly sliced
8 garlic cloves, thinly sliced
1 1/2 teaspoons Diamond Crystal or 3/4 teaspoons Morton kosher salt, divided
12 spring onions, thinly sliced on a deepdiagonal
2 tablespoons Dijon mustard
60g Parmesan, finely grated (about 300g )
Freshly ground black pepper
How to make Triple-Threat Onion Galette
Back to contentsWhisk sugar, salt, and 190g flour in a medium bowl to combine. Add butter and toss to combine. Using your hands and working quickly, rub and smash butter into flat, irregular pieces (be careful not to overwork; you don’t want to soften the butter too much).1 Drizzle 80ml cold water over and mix with a rubber spatula, smashing in butter, until dough mostly comes together—it will be dry and shaggy.
Turn out dough onto a lightly floured surface. Working quickly and using a rolling pin and your hands, press dough together to form a mass. Roll dough into a rough square about 1/2" thick. Fold in half into a rectangle, then once again to make a small square. Press down on the dough with rolling pin to make it hold together. Roll dough out once more to make a rough square about 1/2" thick. Repeat folding process, taking your time to make it neat as this will be your final fold. Using rolling pin, gently flatten dough, rotating as needed, to make a 6"-diameter disk.
Dust surface with more flour and roll disk into a 14"-diameter circle or oval about 1/8" thick. Fold dough in half, then in half again to make a rough triangle (this will make it easier to move). Slide onto a parchment-lined baking sheet and unfold. Chill while you make the filling.
Do Ahead: Dough can be made 3 days ahead. Wrap 6" disk tightly and chill until ready to roll out.
Place a rack in middle of oven; preheat to 191°C. Heat 45ml butter in a medium skillet over medium until foaming, about 1 minute. Reduce heat to medium-low; add onion, garlic, and 1 teaspoon Diamond Crystal or 1/2 teaspoons Morton salt, and stir to combine. Cover and cook, stirring occasionally, until onion is tender and just beginning to brown, 6–8 minutes. Uncover and continue to cook, stirring occasionally and adding a splash of water if onion begins to stick, until golden brown in spots, about 5 minutes more. Transfer onion mixture to a plate; reserve skillet.
Melt remaining 1 tablespoon butter in reserved skillet (no need to wipe out) over medium heat. Remove from heat and add spring onions and remaining 1/2 teaspoons Diamond Crystal or 1/4 teaspoons Morton kosher salt. Toss spring onions until coated in butter.
Remove dough from refrigerator and, using a small offset spatula or a spoon, spread mustard in a thin layer over dough, leaving a 1 1/2"–2" border around the edges. Scatter onion mixture over mustard and sprinkle with Parmesan; season with pepper. Cutting from edge of dough to the start of the mustard and filling, make slits in border of galette at 2"–3" intervals. Fold flaps up and over filling, slightly overlapping. Scatter spring onions over. Bake galette until crust is deep golden brown and spring onions are lightly charred, 45–50 minutes. Using parchment paper, slide galette onto a cutting board and cut into wedges.
Do Ahead: Onion can be cooked 3 days ahead; transfer to an airtight container, then cover and chill. Galette can be assembled 1 hour ahead; chill.
Disclaimer
While every effort has been made to ensure the information is accurate and up to date, individual needs may vary and dietary requirements can differ based on personal health conditions. Always check food labels and allergen information before preparing or consuming any recipe. If you have specific health concerns, allergies, intolerances, or are following a medically prescribed diet, seek advice from your GP, pharmacist, or a registered dietitian before making significant changes to your diet or lifestyle.
Article history
The information on this page is peer reviewed by qualified clinicians.
28 Jan 2026 | Originally published
Authored by:
UK recipe editors
Peer reviewed by
UK recipe editors

Ask, share, connect.
Browse discussions, ask questions, and share experiences across hundreds of health topics.

Feeling unwell?
Assess your symptoms online for free
Sign up to the Patient newsletter
Your weekly dose of clear, trustworthy health advice - written to help you feel informed, confident and in control.
By subscribing you accept our Privacy Policy. You can unsubscribe at any time. We never sell your data.