Food waste cooking sometimes tests the boundaries of what most folks find appealing. A dish of pasta tossed with radish top pesto will probably please most eaters, while sour milk cheese may leave some scratching their heads. Coffee flour will likely rest in the camp of the former. Made from grinding discarded coffee cherries into a dark powder, wheat-free coffee flour can be added to baked goods for a slightly bitter citrus flavor. Unlike typical food waste cooking, you won’t find yourself with a mountain of coffee cherries waiting to be milled into coffee flour after making your morning pot. The fragrant flour is currently produced by aptly named brand CoffeeFlour and can be purchased online. While a few other coffee flour outliers have surfaced, CoffeeFlour seems to be the best way to bake with the stuff, short of befriending a coffee farmer to DIY.
Coffee flour’s flavor and sustainable roots aren’t the only reasons to throw a few spoonfuls of the stuff into a batter. According to the manufacturers of CoffeeFlour, the naturally gluten-free flour boasts high levels of iron, protein, and potassium, plus it’s higher in fiber per gram than whole wheat flour. Surprisingly enough, since coffee flour doesn’t taste anything like the coffee you drank this morning, the ingredient is wildly versatile, recipe wise. While it’s recommended that coffee flour be mixed with other flours (with xanthan or guar gum added to gluten free blends) when baking, a finer grind of the flour can be added to ice creams, drinks, and sauces. CoffeeFlour recommends swapping in between 10 and 25 percent coffee flour and increasing moisture within the recipe by 10 to 15 percent.
When I was young, I always wondered why coffee cake didn’t have coffee in it. Now that I know about coffee flour, we’re going to change that. Preheat the oven to 350ºF and butter and flour a 9-inch cake or square baking pan.
In a large bowl, beat 1 cup brown sugar, ½ cup granulated sugar, 1 cup butter, and 1 teaspoon kosher salt until light and fluffy, about 5 minutes. Beat in 5 eggs, one at a time, adding 1 teaspoon of vanilla extract along with the last egg.
In a separate bowl, whisk together 2 cups all purpose flour, ⅓ cup coffee flour, 2 teaspoons baking powder. With a rubber spatula, fold in one third of the flour mixture until just combined, then fold in 1 cup Greek yogurt. Fold in half the remaining flour mixture, then another cup of yogurt. Add the rest of the flour and fold until just combined.
Scrape the batter into the baking pan. In a small bowl mix together ½ cup brown sugar, ¼ cup coffee flour, 2 teaspoons ground cinnamon, ½ teaspoon kosher salt, and 3 tablespoons softened butter. Sprinkle the mixture over the cake.
Bake for 40-50 minutes, until the cake is cooked through. The coffee flour will make the batter very dark, so stick a toothpick in the center of the cake after 40 minutes. When the toothpick comes out with a few crumbs, the cake is finished.