Sweet potato that tasets like chestnut?

It's not exactly a sweet potato that tastes like chestnut, but there's a close relative that does! It's called a Yacon.

Yacon (pronounced "yah-con") is a root vegetable from the sunflower family, and it's sometimes called a "sweet potato with a chestnut flavor." It has a slightly sweet taste, with notes of caramel and a hint of nuttiness, reminiscent of chestnuts.

Other options that might be similar to chestnuts:

* Purple Yam: While not exactly chestnut-like, purple yams have a starchy, earthy flavor that some find comparable. They are also very colorful and delicious.

* Jicama: This crisp, crunchy root vegetable has a mild, slightly sweet flavor with a hint of earthiness. It's not directly chestnut-like but might appeal to those who enjoy the earthy notes.

Keep in mind that these are all different vegetables with unique flavors. You might enjoy trying them all to see which one best suits your taste preference!