It all started with an innocent batch of muffins. I had to turn the oven on to make dinner, so while I was already heating the apartment I figured I may as well make some blueberry-coconut muffins (and bread, and granola, and cookies… but that’s another story). I didn’t think much of it–I wanted blueberry muffins, and the recipe was vegan and looked yummy. The coconut was just a bonus.
Turns out the coconut was amazing.
The tart berries with the rich, sweet coconut was a match made in heaven. Or at least, you know, on match.com. So I devoured those muffins and made another batch, all the while scheming about other ways to unite these two ingredients which were clearly made for each other. My vision was a coconut cookie crust with a creamy, blueberry-studded top. It needed not only shredded coconut but also coconut milk. And the bottom should be flaky, not chewy. And the top had to be solid enough to hold the blueberries in place but not be cakey.
Usually when I build up these exacting visions of desserts (no, it’s not weird that I do that frequently), it takes a few iterations to get it right. But the magic of blueberry and coconut made these bars both beautiful and meltingly delicious–creamy and buttery and sweet with bright bursts of blueberry. They disappeared immediately and I’ve already had requests for more. I’ll be happy to oblige, as long as I get some too!
(I know, I know–I started raving about muffins and then left you hanging. The inspirational recipe is here and is definitely worth making.)
The Science: Toasted coconut
Shredded coconut by itself is really just white and papery, making it hard to enjoy even though I love coconut so much. But stick that uninspiring paper in the oven and something magical happens: it turns golden and crispy, filling the whole kitchen with the irresistible warmth of somewhere tropical where alarm clocks don’t exist and all drinks come with umbrellas.
The instant vacation is thanks to chemistry, of course! The typical sweetness of coconut comes from molecules called lactones, which we also encounter in peaches. The atoms in this kind of molecule have a closed ring of atoms, with one oxygen atom in the ring and another oxygen sticking out.
The heat of toasting changes the chemical structure of the important flavor molecules, making the toasty coconut taste like something entirely different. After its stint in the oven, lactones are no longer the dominant molecule–you have pyrazines and pyrroles and furans. These are some of the same molecules that you get from caramelization reactions, so you probably recognize the flavors.
Looking at the molecules barely hints at the extent of the transformation, though. Taste a piece of untoasted coconut next to some of the golden toasted goodness and you’ll see what I mean. The untoasted pieces mostly just taste sweet, but the toasted coconut has all sorts of other flavors–nutty and caramel-y stand out for me. It’s almost like magic–but really it’s science!
The Recipe: Coconut-blueberry cream bars
I made this in a 9-inch cake pan with a removable bottom, which worked wonderfully, but you could also use a regular cake pan or an 8-inch square pan. I loved just throwing everything into the food processor for both the cookie and the topping, since fewer dishes are always a good thing!
Yield: 12 bars
Coconut shortbread cookies
1/2 cup sweetened shredded coconut
3/4 cup unsalted butter, chilled
1/3 cup sugar
3/4 teaspoon salt
1/2 teaspoon vanilla extract
1 cup all purpose flour
Spread the shredded coconut in a thin layer on a baking sheet. Toast in a 350 degree oven for about 8 minutes, until it is golden and crispy and your kitchen smells amazing. Cool the toasted coconut to room temperature (I stuck mine in the freezer for a few minutes).
Place the cooled toasted coconut in a food processor and grind it into a coarse powder. Add the butter and sugar and pulse until well combined. Add the salt and vanilla, then the flour in two additions. The dough should be crumbly.
Press the dough into a 9-inch round or 8-inch square pan and bake at 350 degrees for 25 minutes, until the edges are browning and the cookie is firm to the touch. While it is baking, prepare the topping (below).
Coconut cream topping
1 cup sweetened shredded coconut
2 large eggs
1/2 cup sugar
1/8 tsp salt
1/3 cup coconut milk
1/2 teaspoon vanilla extract
Process the shredded coconut in the food processor until it is in small pieces. Add the rest of the ingredients and pulse until the mixture is smooth.
1 pint blueberries
1/4 cup sweetened shredded coconut
When the cookies are done, pour the cream topping into the pan on top of the shortbread. Generously drop blueberries into the topping, and sprinkle with coconut. Bake for 25 minutes at 350 degrees, until the edges are slightly brown and the filling is set.