Step 1

Place potato in a large pot and cover with water; bring to a boil. Reduce heat to medium-low and simmer until tender, about 15 minutes. Drain. Cool potato until easily handled, about 5 minutes.

Step 2

Peel potato and mash into a bowl. Stir in vanilla extract. Stir in confectioners' sugar until mixture is smooth and firm. Fold in coconut.

Step 3

Grease a 9-inch cake pan with cooking spray. Spread potato mixture in the pan. Refrigerate until set, about 1 hour. Cut into squares.