Make the pastry: Pulse flour and salt in a food processor. Add butter until crumbly. Add ice water until it comes together; shape into a disc and chill.
STEP 2
Roll out dough into a round, fit into tart pan and chill.
STEP 3
Preheat oven to 375°F. Bake crust with parchment and weights until golden, then cool.
STEP 4
Cook onions in butter until soft, then add cooked bacon and herbs. Spread in crust with cheese.
STEP 5
Whisk cream, eggs, and seasoning; pour over filling and bake until set. Cool before serving.