The 2020 January transfer window has closed after a month that has seen clubs ransack one another for reinforcements to strengthen their squads for the business end of the season.A series of high-profile players had been on the move by the time the window slammed shut at 11 PM GMT, with the majority of clubs opting for loans instead of permanent transfers. Inter Milan, under the leadership of Antonio Conte, were one of the busiest clubs in the continent as they signed the likes of Christian Eriksen, Ashley Young, and Victor Moses to bolster their squad for the Serie A title battle that lies ahead of them.Premier League clubs like Manchester United, Arsenal, and Tottenham Hotspur were active in the final days of the window, making key temporary and permanent signings to aid them in their race to a Champions League berth.Meanwhile, big names like Krzysztof Piatek, Erling Haaland, Paco Alcacer and Bruno Fernandes all put an end to their sagas by securing moves to various clubs across the continent in the last month.In this article, we review five of the most expensive signings across Europe in the recently-concluded January transfer window:#5 Steven Bergwijn (PSV-Spurs, £25m)Steven Bergwijn (R) after scoring against Manchester City in his debut for Tottenham HotspurTottenham Hotspur signed Dutch forward Steven Bergwijn for £27 million from PSV Eindhoven two days before the end of the January transfer window.Jose Mourinho was aiming to bolster his attacking options after Harry Kane was ruled out of action until at least April due to a hamstring injury. The Portuguese tactician had been hoping to sign a player who predominantly plays on the left wing and appears to have fulfilled his ambitions by signing Bergwijn.The Netherlands international signed a five-and-a-half-year deal with the north London giants and inherited the number 23 shirt previously worn by Christian Eriksen before he made his switch to Inter Milan last month.250 - Steven Bergwijn’s opener for Spurs saw him become the 250th player to score on his debut in the @premierleague, and the 13th Dutchman to do so. Clogs. #TOTMCI pic.twitter.com/31FhpRRSYk— OptaJoe (@OptaJoe) February 2, 2020The 22-year-old, who became Mourinho's third addition of the winter after Gedson Fernandes and Giovani Lo Celso (move made permanent), came through the ranks at PSV and made his first-team debut at 17. He tallied 31 goals in 149 appearances for the club and won three Eredivisie titles during his spell with the Dutch giants.Bergwijn left the Spurs faithful with nothing to regret as he scored on his debut appearance for the club and helped them to an emphatic 2-0 home win over reigning champions Manchester City in the Premier League.The former PSV man was seen beautifully controlling Lucas Moura's effort on his chest before making a shot into the bottom right-hand corner, beating Ederson and putting his new club on their path to one of their most memorable wins of the campaign.