Yoane Wisse, Bryan Mbeumo, Christian Norgaard and Fabio Carvalho struck the goals for the Bees.
Frank said, "Very good performance in many ways. It is not easy to win away from home in the Premier League. Coming here and winning 4-0 against a team that has to put everything into avoiding relegation, I am very happy with our performance and with the way we went forward and the chances we created. A clean sheet is very important. Overall a happy man."
On back-to-back Premier League wins for the first time since April, the Dane continued: "That's crazy. We have had a good season overall. Not through the roof, but good. We haven't had back-to-back wins so that is quite strange. To get over the line and get the win is important.
"We haven't changed that much. We tried to be consistent with our messaging to players."
On aiming for European places, Frank said: "That is a big, big aim. We have dreams, we want to aim as high as possible no doubt about that and we want to push. It is the first time we had back-to-back wins, we need more further down the line before we can really dream. We are in a good place and can keep pushing."