sliced bread

US /ˌslaɪst ˈbred/
UK /ˌslaɪst ˈbred/
"sliced bread" picture
1.

pain de mie, pain tranché

bread that has been cut into slices, typically by a machine, before being packaged

:
She bought a loaf of sliced bread for sandwiches.
Elle a acheté une miche de pain de mie pour les sandwichs.
Toast is often made from sliced bread.
Le pain grillé est souvent fait à partir de pain de mie.
2.

la meilleure chose, une invention géniale

used to refer to something that is considered to be an excellent invention or idea

:
This new app is the best thing since sliced bread.
Cette nouvelle application est la meilleure chose depuis le pain de mie.
He thinks his idea is the best thing since sliced bread.
Il pense que son idée est la meilleure chose depuis le pain de mie.