Lupin was surprised that Harry had tasted Butterbeer when, as far as the professor knew, Harry had never been to Hogsmeade.[12] This was untrue as Harry had been to Hogsmeade previously when he sneaked in and had tried Butterbeer at The Three Broomsticks.

In addition to treacle tart, as one answer mentioned, Harry enjoys French onion soup. In the seventh book the narration notes that after they are kinder to Kreacher, his cooking improves, and “today’s French onion was as good as Harry had ever tasted.”

This classic dish is often served at Hogwarts feasts, so obviously it's got to be good. In fact, all of the Hogwarts feasts sound amazing... though the fact that it's cooked with house-elf labor disqualifies it from rising higher on the list (though Dumbledore does eventually pay Dobby, so if it's made by Dobby, yay).

Remember when there wasn't enough ice cream on Dudley's Knickerbocker glory, and he pitched a fit, so Harry got to eat the rest? That's the taste of happiness right there. This may not be a magical dish, but Harry was happy when he ate it, so it probably tasted great.

Harry Potter tried them for the first time on the Hogwarts Express, at the start of his first year, when he famously impressed Ron Weasley by buying some of everything on the trolley

Treacle tart is a traditional English dessert, made predominately of shortcrust pastry and golden syrup. The tart is normally served hot with a dollop of clotted cream. It can also be served with ordinary cream, custard, or yoghourt. Treacle tart can also be served cold. It is a favourite dessert in the wizarding world and also a personal favourite of Harry Potter,[1] who likes it so much that he smells it when he is in the presence of Amortentia.