Kasper, 18, was selected by the Red Wings in the first round (eighth overall) of the 2022 NHL Entry Draft, held at Bell Centre in Montreal on July 7-8, and is currently participating at Detroit's Development Camp from July 10-14 at the BELFOR Training Center inside Little Caesars Arena. The 6-foot-1, 183-pound center spent the majority of the 2021-22 season playing for Rögle BK in the Swedish Hockey League, tallying 11 points (7-4-11) and 17 penalty minutes in 46 games. His 11 regular-season points were the most of any under-18 skater in Sweden's top professional league. Kasper also recorded six points (3-3-6), a plus-four rating and nine penalty minutes in 13 postseason contests as Rögle reached the SHL Semifinals, falling to eventual champion Färjestad in six games. He helped Rögle clinch its first-ever Champions Hockey League title, notching six points (2-4-6) in 12 appearances during the competition. Additionally, Kasper racked up 13 points (6-7-13) and 10 penalty minutes in 12 games for Rögle's under-20 squad, along with a goal and two assists in one playoff game with the team.
A native of Innsbruck, Austria, Kasper became the highest Austrian-born pick since former Red Wings forward Thomas Vanek, who was selected fifth overall by the Buffalo Sabres in the 2003 NHL Entry Draft. On the international stage, Kasper contributed a pair of assists in seven games for his country at the 2022 IIHF World Championship in Helsinki and Tampere, Finland. He also captained Austria at the 2022 IIHF World Junior Championship, appearing in two games before the tournament was postponed due to COVID-19 concerns. Kasper previously represented Austria at the 2021 IIHF World Junior Championship, finishing with one assist in four games.
Prior to the start of the 2020-21 season, Kasper moved to Sweden and joined Rögle, where he was a teammate of Red Wings defenseman Moritz Seider. Kasper notched one assist in 10 regular-season games before skating in six playoff contests as Rögle clinched a place in the SHL Final. He also posted two goals in six games for Rögle's under-20 team and eight points (3-5-8) in seven games on the under-18 circuit. In 2019-20, Kasper made his professional debut in Austria with EC KAC II of the Alps Hockey League, picking up two points (1-1-2) in three games. Kasper also compiled 153 points (45-108-153), a plus-111 rating and 40 penalty minutes in 66 games with EC KAC II's Under-18 squad from 2017-20, in addition to 30 points (12-18-30) in 16 postseason appearances.
