*If using frozen blueberriesbe sure to thaw and drain them first before adding to the coffee cake batter.
Preheat the oven to 350°F. Grease a 9×13-inch cake pan.
In a medium mixing bowl, combine the almond and millet flours, sugar, baking powder, and salt. In a large bowl, lightly beat the eggs with a fork until the yolks and whites are mostly mixed together. Then add the milk, sour cream, melted butter, and vanilla. Add the dry ingredients to the wet ingredients and stir with a wooden spoon until just mixed. Fold the cream cheese cubes into the batter. Gently fold in the blueberries, taking care not to squish them. Spoon the batter into the prepared pan, spreading it out evenly.
To make the topping, add the butter, brown sugar, quinoa flakes, and cinnamon to a small bowl. Cut them together with a pastry cutter or a fork. Then mix in the chopped walnuts. Using your fingers, spread the topping evenly over the batter.
Bake the coffee cake for 35-40 minutes, or until an inserted toothpick comes out clean. Let cool for about 15 minutes before serving.