usage - What does 意外と mean?

I heard the expression [意]{い}[外]{がい}といい in a video. I know that 意外に expresses something you didn't expect:

意外においしいよ。
It's delicous! (and I didn't expect that)

Why did I hear 意外と instead of 意外に? Is that a specific dialect? Or, is it standard Japanese?

Answer

“いがいといい” is “[意外]{いがい}と[良]{い}い” (unexpectedly good).

意外と is a less traditional synonym for 意外に (unexpectedly), the latter being the 連用形 (continuative form) of the na-adjective 意外だ.