Julen Lopetegui's men entered the match top of Group G with 19 points, three more than second place Italy. Liechtenstein, on the other hand, sat rock bottom having failed to register a single point from the World Cup qualifying campaign.
It took the visitors just three minutes to open the scoring. Silva swung in a cross from the right and Ramos rose highest to power a header past the hapless Peter Jehle.
Morata doubled Spain’s lead after 15 minutes following nice play on the right flank allowing Iniesta to deliver a cross into the box. Morata, having just headed over the bar, this time made no mistake and directed past the Liechtenstein goalkeeper.
One minute later Isco netted the third. Morata stole the ball after a mistake from Jehle and rolled a pass into the path of Isco. The Real Madrid man, who is in fine form, had an open goal and calmly slotted into the net.
Silva got on the scoresheet after Thiago Alcántara earned a dangerous free kick on the edge of the box. The attacking midfielder stepped up and expertly bent a strike into the top right corner.
A rare opportunity for Liechtenstein came just before the break. Nicolas Hasler played a ball back into the path of Michele Polverino, who side-footed a tame strike towards goal that De Gea comfortably saved.
Half-time substitute Aspas made an immediate impact on 51 minutes. Pedro fired in a cross towards Morata, who spurned the initial opportunity as his header rebounded back off the bar, but Aspas was on hand to tap in.
Morata did bag his second 3 minutes later when Aspas fizzed a delightful ball into his feet, he easily turned in the box and squeezed a strike past Jehle into the bottom right corner.
The seventh came after the home side's goalkeeper could only parry a long range strike into the path of Aspas, who managed to maneuver his way past a wall of Liechtenstein defenders and fire in at the near post.
The night finished on an unfortunate note for the hosts. Deulofeu tooks a cross-field ball on the volley, looking to square across the face of goal, but the cross hit Maximilian Goppel and deflected into his own net.
Spain finished the match with 77% possession as they thrashed Liechtenstein 8-0 to strengthen their place at the top of Group G and guarantee a top-two spot.