The powerful centre recorded her double in the opening 28 minutes to underline the superiority of England's start.
Wales rallied as Alisha Butchers pounced on a charge down and Robyn Wilkins intercepted for another try.
But Amber Reed kicked 10 points to maintain England's quest for a first Six Nations title since 2012.
England travel to second-placed France, who lost 10-8 to Wales last month, for their final match on Friday evening in Vannes, eyeing both the title and the Grand Slam.
"At times we made it a little bit tricky for ourselves but the character of this group continues to show, they keep evolving," England coach Scott Bernard said.
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Ceri Large scored two first-half tries as England made it four wins from four in the Women's Six Nations with a 20-13 win over Wales at Twickenham Stoop.