This not-too-sweet coffee cake is an ode to Portland, Oregon, where hazelnuts, blueberries, and weekend brunches reign supreme. With this cake, you can celebrate and savor all three, anytime, anywhere. — Camilla Saulsbury, Bob’s Red Mill Everyday Gluten-Free Cookbook
Other berries, such as raspberries, blackberries, or cranberries, can be used in place of the blueberries. If using cranberries, increase the amount of cane sugar to ¾ cup.
Other nuts or seeds, such as pecans, almonds, or green pumpkin seeds (pepitas), can be substituted for the hazelnuts.
To make this cake dairy-free, use non-dairy buttermilk in place of the buttermilk and vegetable oil in place of the butter.
In a small bowl, combine hazelnuts, brown sugar and cinnamon.
Preheat the oven to 350 degrees F. Grease a 9-inch square metal baking pan with nonstick cooking spray.
In a large bowl, whisk together the amaranth flour, potato starch, baking powder, baking soda, and salt.
In a medium bowl, whisk together the sugar, eggs, butter, and vanilla until well blended. Whisk in the buttermilk until blended.
Add the egg mixture to the flour mixture and stir until just blended. Gently fold in the blueberries.
Spread half the batter evenly in prepared pan and sprinkle with the filling. Dollop the remaining batter on top of the filling (it need not cover the filling completely).
Bake in the oven until a toothpick inserted in the center comes out clean, 28 to 33 minutes. Let cool completely in pan on a wire rack.