I'm hosting an event on Tu B'av and I need to decide on the menu. Are there any foods that are particularly appropriate for the holiday?
I can find no foods that are particularly appropriate for the holiday. In all the descriptions of the day, see for example here there is no mention of special foods (remarkably for a Jewish festival).
Tu B'Av certainly has links to marriage and matchmaking which explains the reference to wedding cake above.
The nights begin to get longer from Tu B'Av which leads to an increase in Torah learning at night which is a special time for learning. This contributes to the happiness for which Tu B'Av is known. So maybe the idea would be to eat foods made from flour based on the mishnah in Avos 3(17) אם אין קמח, אין תורה.