As a sophomore, Laszewski led his team to the New England Preparatory School Athletic Council (NEPSAC) Class AAA title and was named MVP.

[2] In his final season, Laszewski helped his team to a school-record 31 wins and another Class AAA title, where he won MVP.

[3] A consensus four-star recruit, he committed to play college basketball for Notre Dame over offers from Arizona, North Carolina, Wake Forest and Wisconsin.

[7] As a junior, he averaged 13.3 points and 7.3 rebounds per game, earning All-Atlantic Coast Conference (ACC) honorable mention.

Laszewski's father, Jay, and his older sister, Abby, played college basketball at Wisconsin.