Vanasch has been involved in hockey from an early age; his father "Jean" created the youth school of the "Royal Evere White Star Hockey Club". He did all his classes until the first team with which he won several titles (grass and indoor). When the club got relegated to Division 1, at the end of the 2006–2007 season, he went to play at the "Royal Penguin Hockey Club Nivellois". He played for two seasons before getting a transfer to KHC Leuven. From the 2010–2011 season onwards, he started playing for the Waterloo Ducks. In 2014, he made a transfer to the Netherlands to Oranje Zwart.[1] He played there until 2016, when he returned to the Waterloo Ducks.[2]
In the 2018–19 Euro Hockey League, Vanasch's Waterloo Ducks became the first Belgian club to win the Euro Hockey League.[3][4] In January 2020, it was announced he would play for Rot-Weiss Köln in Germany from the 2020–21 season onwards.[5] After three Bundesliga titles in three years he returned to Belgium and signed a three-year contract at Orée.[6]