This brownie sundae SLAPS.
The use of "this slaps" to express enjoyment over something is thought to have originated in the early 2000s Bay Area hip-hop scene. Initially, people used the term to describe impactful music with a strong beat or bassline. In the 2010s, "slaps" began to spread beyond the music community, finding its way into everyday conversations.
Today, people use the phrase "this slaps" or "slaps" to describe anything they find good or enjoyable. It retains its musical roots but has expanded to cover a wide range of contexts. A fan may say the latest episode of their favorite show “Slaps” because it's so entertaining. Similarly, someone might say, "This pizza slaps," to convey that the food is exceptionally tasty.