Homemade gluten-free flour mix
In gluten-free baking, the ratio of starches to grain flours is important to achieving the right structure. This is especially important for cakes that depend on gluten to trap air bubbles, allowing the batter to expand and rise as the cake bakes.
To render this Martha Stewart recipe gluten-free, I based myself on Gluten-Free Girl's post on making an all-purpose gluten-free flour mix. She suggests a ratio of 60:40 starches:whole grain flours (by weight), so that's what I did, using potato starch and rice flour as my "starches" and buckwheat flour and millet flour as my "whole grain flours".
This worked very well, but perhaps the mouthfeel was just slightly starchier than I would've liked. Maybe next time, I'd do a 50:50 mix, or even 40:60. We'll see.
Since the cake is gluten-free, the batter doesn't have enough structure as it bakes to support the berries, so they sink into the cake, even if you coat them in flour.
To bake this cake, I used an 8x8-inch square metal brownie pan, which I lined with parchment all over and with overhangs so the batter wasn't touching the pan at all. If you would prefer to properly prepare the pan before baking, butter the pan and dust with flour. You can also line the bottom with parchment to avoid it sticking.
Gluten-free raspberry cake
- 125 grams (1 cup) buckwheat flakes
- 167 mL (⅔ cup) whole milk (3.25 % fat)
- 58 grams (¼ cup) unsalted butter
- 100 grams (½ cup) granulated sugar
- 100 grams (½ cup) light brown sugar
- 1 large egg(s)
- 5 mL (1 teaspoon) pure vanilla extract
- 96 grams (¾ cup) all-purpose gluten-free flour mix I used 19 grams of millet flour+19 grams of buckwheat flour+29 grams rice flour+29 grams potato starch
- 2.5 mL (½ teaspoon) baking powder
- 2.5 mL (½ teaspoon) baking soda
- 1.25 mL (¼ teaspoon) ground allspice
- 2.5 mL (½ teaspoon) Diamond Crystal fine kosher salt
- 260 grams (2 cups) Fresh raspberries
- 130 grams (1 cup) Fresh raspberries
- 15 mL (1 tablespoon) granulated sugar
- Preheat the oven to 350°F. Line an 8-inch square metal pan with parchment, leaving an overhang on either side.
- In a medium bowl, combine the milk and 2 cups buckwheat flakes and let sit for about 5 minutes.
- Meanwhile, in the bowl of an electric mixer fitted with the paddle attachment, cream the butter and the sugars.
- Add the egg, beat again, scraping down the sides as needed, and then add the vanilla. Beat until creamy and smooth.
- Add the buckwheat flake/milk mixture and beat.
- In a separate bowl, whisk together the flours, starches, baking soda and powder, salt, and the spice, and then add them into the mixer bowl. Beat on low to combine, then increase the speed to medium for one more minute.
- Pour the batter into the prepared pan, sprinkle with 2 tablespoon cane sugar and 2 tablespoon buckwheat flakes, then scatter with raspberries, and top with the remaining cane sugar and flakes.
- Bake for about 55 minutes or until a cake tester inserted into the center comes out clean.
- Let cool before serving.
- Prepare a raspberry topping before serving by lightly mashing the extra cup of berries with a tablespoon of sugar. Top pieces of the cake with this chunky raspberry sauce.