Garcia scores twice as Man Utd ease past Spurs to lift first FA Cup
United were beaten by Chelsea in last year's final, but they made amends with a swaggering display in the north London sunshine.
Ella Toone started United's goal spree with a fine finish late in the first half.
Rachel Williams headed home soon after the interval before a blunder by Tottenham keeper Becky Spencer presented Garcia with the killer third goal three minutes later.
Garcia netted her second late on to put the seal on United's sublime performance as they erased the bitter taste of a disappointing season in the Women's Super League.
"We are obviously not where we want in the league right? But we are history makers for Manchester United. I didn't need to remind the owners of that, they know. There is a lot of support and love for our team and the growth," United boss Marc Skinner said.
"We want to compete for titles but you all know how important adding that first piece of silverware is. We've got nothing but growth ahead."
It is the first time since Birmingham's victory in 2012 that the Women's FA Cup has not been won by Arsenal, Chelsea or Manchester City.
"In all honesty I felt that first half was just frustration because we didn't score. I thought we offered more of a threat, we controlled most of their threat," Skinner said.
"As much as I am exhausted now it is a magical feeling. I told Tooney on the podium you have to remember it, because it comes and goes too quick. From start to finish today we thoroughly deserved our success."
Skinner's side started their march towards the club's first major women's trophy confidently against a Tottenham team playing in their maiden FA Cup final.
Toone fired over the bar, while Tottenham's Martha Thomas made an excellent block to clear Millie Turner's header off the line.
Toone curled narrowly wide with the eighth shot of United's opening salvo.
Their pressure was rewarded three minutes into stoppage time when Toone patiently wove her way forward before lashing a superb long-range strike into the top corner.
United doubled their advantage in the 54th minute when Williams rose highest to meet captain Katie Zelem's free-kick and directed her towering header into the back of the net.
Three minutes later, Spencer completely mishandled a clearance, directing her pass straight at Garcia, who gleefully accepted the gift with a simple finish.
Tottenham were still looking for their first shot on target until skipper Bethany England clipped the crossbar with her header.
But Tottenham's hopes of salvaging some pride were shattered in the 74th minute as Melvine Malard's cross was rifled home by Garcia to start the United celebrations in earnest.
