French onion tart
French onion tart combines crisp shortcrust pastry with a tender filling of slowly cooked onion, cream and eggs. Blind-bake the shell to keep the base crisp beneath the moist filling.
Additional 40 min — cooling and chilling
How to make it
Prepared 0 of 6 steps
Make the shortcrust pastry
Reserve 20 g flour for rolling. Rub the rest with 125 g cold butter and 3 g salt to coarse crumbs. Add cold water and bring together quickly without prolonged kneading. Flatten, wrap and chill for 40 minutes.
Cook onions slowly
Thinly slice onions into half-rings. Cook in remaining 25 g butter with thyme leaves and 2 g salt for 30–35 minutes over medium-low heat until soft and golden without burning. Cool.
Bake the base
Heat the oven to 190 °C. Roll pastry on reserved flour and line a 24 cm tart tin. Prick the base, add parchment and ceramic weights and bake for 18 minutes, then without weights for 7 minutes more.
Mix the filling
Mix eggs, cream, remaining 2 g salt, pepper and nutmeg without foaming. Fold in cooled onions and coarsely grated Gruyère. Do not add very hot onions to raw eggs.
Bake the tart
Reduce to 170 °C. Fill the partly baked shell and bake for 30–40 minutes until edges set and the centre wobbles as one mass without liquid custard, reaching at least 71 °C.
Cool before slicing
Rest on a rack for 15 minutes before unmoulding and slicing so the filling firms without flowing out. Bacon, olives, tomatoes and lettuce are not included.
Little hint
Soften onions separately first; raw, tough rings will not cook enough in the delicate filling. Do not fill a raw pastry case if you want a crisp base.
Frequently asked questions
What should I watch out for when cooking?
Soften onions separately first; raw, tough rings will not cook enough in the delicate filling. Do not fill a raw pastry case if you want a crisp base.
How should I prepare the ingredients?
Reserve 20 g flour for rolling. Rub the rest with 125 g cold butter and 3 g salt to coarse crumbs. Add cold water and bring together quickly without prolonged kneading. Flatten, wrap and chill for 40 minutes.
