Apple. The classic free dessert in a taverna was a sliced apple with cinnamon sprinkled on top, and it was delicious. The orchards of the Pelion peninsula produce most of Greece's apples, including the rare firiki. A brewery in Athens, Μηλοκλέφτης or Milokleftis, has started making apple cider.
Although the apple tree originated in Central Asia, there are fossil records of apples in Anatolia going back to 6500 BC. Greeks have known about apples at least since the 7th century BC, but they were relatively rare and expensive, and adored as the fruit of all fruits (in fact, in several ancient languages, 'apple' was synonymous with 'fruit', leading to modern disagreements over exactly what kind of fruit grew in the Garden of Eden or in Gaia's Garden of the Hesperides).
Gaia gave her golden apples of immortality to Zeus and Hera as a wedding gift, and they became a must at ancient weddings--hence the famous Apple of Discord that led to the Trojan War. In the 6th century BC when the sage Solon laid down his sumptuary laws against Athenian extravagance, one rule was to limit newlyweds to one apple that they had to share.
They were sacred to Aphrodite, who gave golden apples to Hippomenes, so he could win the fair and fleet Atalanta in the footrace for her hand. Although she was the fastest, Hippomenes distracted her during the race, dropping golden apples that she couldn't pass by.
Pythagoras noted that when an apple was split open, the seeds formed a five pointed star, a pentagram, which in his philosophy represented marriage, because it was the sum of two (matter) and three (the ideal number). But because of the pentagram, one of the keys of knowledge, his followers were said to have shunned them, as they did fava beans.
Image by PD art