The Bees showcased their attacking flair as Yoane Wissa, Bryan Mbeumo, Christian Norgaard, and Fabio Carvalho all found the net at the King Power Stadium.
Frank praised his squad's performance, highlighting their dominance on the road. "It was a very good performance in many ways," he said.
"Winning away in the Premier League is never easy, and to come here and beat a relegation-threatened team 4-0 is something I'm very happy with. We pushed forward, created chances, and kept a clean sheet, overall, I'm a happy man."
The victory marked Brentford's first back-to-back Premier League wins since April, a milestone Frank found surprising yet satisfying. "That's crazy when you think about it," he admitted. "We've had a good season so far, not spectacular, but solid.
"To finally string two wins together feels important. We haven't changed much; we've just stayed consistent with our approach."
Brentford's emphatic display began early, despite a fleeting Leicester threat when Jamie Vardy's weaving run tested goalkeeper Mark Flekken. However, the Bees soon took control. Wissa opened the scoring with a clinical finish off a clever Mikkel Damsgaard flick, the ball ricocheting in off the post.
Mbeumo then doubled the lead, cutting inside and curling a beauty past Mads Hermansen on 27 minutes.
Leicester's defence crumbled further when Norgaard nodded in a Mbeumo free-kick just past the half-hour mark. By stoppage time, the home crowd was thinning out, missing a near-miss from Kevin Schade's header onto the woodwork. The Foxes, trailing at halftime in their eighth home Premier League game this season, a league-high, couldn't muster a response after the break.
Late in the game, substitute Fabio Carvalho sealed the rout, tapping in from close range after more fine work from Mbeumo, who finished with a goal and two assists. Leicester, drenched in rain and disappointment, slumped to their 10th defeat in 11 league matches, piling pressure on manager Ruud van Nistelrooy as they languish in 19th place.
For Brentford, four consecutive away wins have transformed their season, lifting them into the top half of the table.
Frank remains ambitious but grounded about European aspirations. "We have dreams and want to aim high, no doubt," he said. "But this is only our first set of back-to-back wins. We need more before we can seriously dream of Europe. For now, we're in a good place and will keep pushing."
In a recent X update, Brentford celebrated the result, posting: "Four goals, three points, and a perfect night in Leicester! The Bees are buzzing!"
Meanwhile, Mbeumo took to X to thank the travelling fans, writing: "Another big win on the road - you lot were class again. Onto the next one!" Leicester, however, stayed silent on the platform, reflecting the gloom engulfing the club.