As nice as pie
Definition 1 of 1
Pro Tip 1/3Cultural Positivity
The phrase is often used in British English to express that someone is being very friendly. 
When I got lost in London, the police officer was as nice as pie while helping me.
Pro Tip 2/3Non-literal Meaning
Remember, the phrase is not about pies. It's a metaphor for someone's pleasant demeanor. 
Despite her tough look, she's as nice as pie once you get to know her.
Pro Tip 3/3Informal Setting
Use this expression in casual conversations, not in formal or academic contexts. 
At the family BBQ, my uncle was as nice as pie to all the guests.