Central defender Vitorino Hilton has signed a one-year contract extension with Montpellier.
AC Milan have completed the permanent signing of defender Cristian Zapata from Villarreal for an undisclosed fee.
The 54-year-old former England captain turned down a lucrative move to npower Championship side Barnsley this week to remain in the Highlands.
Inverness sit second in the Clydesdale Bank Premier League following an impressive campaign so far and Butcher is confident there is more to come.
He told Moray Firth Radio: "We are halfway through the season and we are in a fantastic position. I want us to make sure that we finish the season on a real high.
"We want the second half of the season to be better than the first.
"If we can do that it's going to be the best season of my career as a manager, and certainly for a lot of the players as well."
Butcher said he spurned the advances of the Tykes despite a tempting financial offer.
He added: "I've decided to stay here and I feel very happy about that.
"Barnsley were absolutely magnificent to me, they are a lovely club and looked after me very well.
"They made me a brilliant offer which, financially, was very, very good. And I've still turned that down.
"It's nothing to do with the finances or anything like that. It was just a football decision, that what we have at Inverness is just incredible and special. I wanted that to continue."