The phrase "a pancake overlooking" doesn't mean anything, really. In this sentence, "after a pancake" means "after having/eating a pancake". "Overlook" basically means "to look at from a higher viewpoint", or to "look down at" something. In other words, the place where they would eat the pancake would be somewhere ABOVE the Grote Market, allowing them to have a nice view of it. Another way of writing this sentence could be: "After eating a pancake while having a nice view of the energetic and beautiful Grote Markt, you'll be glad you made the trip." Hope this helps :)

After [eating] a pancake [in a restaurant] overlooking the bustling and achingly pretty Grote Markt, you’ll be glad you made the trip. I assume there is some restaurant overlooking the Grote Markt which serves pancakes. Otherwise, this makes no sense.

I think it means having a pancake and looking out the at Market. I think Garret sums it up.

There is a comma missing after pancake.