After beating England 2-1 in manager Luis Enrique's first game in charge, the new-look La Roja stunned their European counterparts at the Estadio Manuel Martínez Valero.
Asensio, winning his 16th cap on the evening finished with one goal and an incredible four assists - while the central midfield pairing of Dani Ceballos and Saul Niguez showed great promise.
"We're ending a get-together which went really well in every way and with our fans today we have been loved. It was really good playing here," he said after the game.
The Real Madrid man has flourished at club level, winning eight trophies, including the Liga title and two Champions Leagues, and has developed into a jewel on the international stage over the past 12 months.
"I am always trying to give my best on the pitch and if I can score goals, all the better.
"We have played against team that did really well in the World Cup. We saw it as a challenge and these are two important victories."