Barcelona midfielder Thiago, who has been linked with a summer switch to Manchester United, scored the perfect treble before half-time with a header, followed by left and right-foot strikes.
Isco added a fourth from the spot to make Ciro Immobile's early leveller and Fabio Borini's late reply of little consequence with Spain comfortably the best side on the night and throughout the tournament in Israel.
The senior side are the reigning European champions, having defeated Italy last year, and also hold the World Cup, with the youngsters' success demonstrating the nation's clear strength in depth.
Thiago told Sky Sports: "I think it is a perfect tournament. We won all the matches and we played wonderful football too.
"I am very glad for my players and I'm glad for the tournament too.
"The most important thing is to play a good game for the team and for each other.
"All the players played an amazing game and congratulations to the team."