How do I declare and assign a variable on a single line in SQL

I want something like

DECLARE myVariable nvarchar[MAX] = "hello world".

Bonus points if you show me how to encode a quote in the string.

E.g.:

I want the string to read

John said to Emily "Hey there Emily"

my attempt would be

DECLARE myVariable nvarchar[MAX] = "John said to Emily \"Hey there Emily\""