Step 1

Preheat the oven to 325°F.

Step 2

Combine the flour, cocoa, salt, baking powder, cinnamon, ginger, nutmeg and cloves in a mixing bowl.

Step 3

In another mixing bowl, combine the melted butter, brown sugar and granulated sugar.

Step 4

Add the vanilla extract, egg and egg yolk, mix well.

Step 5

Add the sweet potato.

Step 6

Combine well, then add the dry ingredients.

Step 7

Mix in the chocolate chips.

Step 8

Drop large tablespoons of cookie dough onto a baking sheet.

Step 9

Bake for 25-30 minutes.