I'm not sure why this recipe caught my imagination. I'm not usually a fan of gimmicky recipes or strange substitutes for butter and sugar in baked goods. But it did kind of make sense that a cup of sweet, sticky mashed sweet potatoes would work in a brownie. And I just happened to have some already baked sweet potatoes hanging around my kitchen. So I thought, why not? Read on for what happened.

This recipe is from the UK newspaper The Guardian and was developed by baker Dan Lepard. In his headnotes, Mr. Lepard explains that the sweet potatoes maintain the brownie's sweetness and texture while allowing for a little less butter and sugar. He also says that you can further eliminate some sugar and fat by using less chocolate and adding in dried blueberries or sour cherries. But I wanted to test the recipe as simply as possible, so I stayed with the original amount of chocolate.

The recipe is in grams which I really appreciated since weight is better than volume for accurate baking, in my experience. I own a scale that has a gram setting which I use quite often and highly recommend. I did try the recipe by converting the grams to the usual US measurements and found that although I wasn't completely accurate (1 stick of butter is slightly more than 100 grams, for example) it still worked very well. The only change I made was to add a pinch of salt, as I do with nearly all the sweets I make.

So how were they? Simply delicious. Deeply flavorful and dense, they definitely fall into the 'fudgy' category of brownie, which I am partial to. There's no hint of vegetable flavor and they held up really well, even after being frozen.

Here's the thing, though. In researching other brownie recipes, I've discovered that there really isn't much less butter and sugar in this recipe than in many of the typical brownie recipes. For a 8-inch square pan, I used 1 stick of butter and 1/2 cup of brown sugar (packed) which is pretty typical. That said, the cup of heavy, mashed sweet potatoes did add volume, so perhaps there is a slight decrease.

But I wasn't in this to micromanage the sugar and butter, I was just curious if these brownies were good. And they were. I even got to test them on some unsuspecting kids who gobbled them up in an instant. Little did they know they were also getting a dose of vitamin A, too!

• Get the recipe: Dan Lepard's Sweet Potato Brownies from The Guardian

Ingredients in US amounts:
1 stick of butter
8 oz dark chocolate, divided
1 cup mashed sweet potatoes
1/2 cup (packed) brown sugar
2 eggs
2 teaspoons vanilla
3/4 cup flour
1/4 teaspoon baking powder
(pinch of salt)

Related: Dark Fudgy Brownies with a Very Unusual Ingredient

(Images: Dana Velden)