Preheat oven to 350 degrees F (175 degrees C). Line 2 muffin tins with cupcake liners.
Place almonds in a coffee grinder or food processor and grind into a meal.
Combine almond meal, mashed bananas, teff flour, brown rice flour, almond milk, coconut oil, water, and flax seeds in a large bowl. Blend with an electric mixer until smooth. Mix cinnamon, salt, baking powder, and allspice into the batter.
Spoon batter into liners, filling each about 2/3 full. Lightly press a walnut piece on top each one.
Bake in the preheated oven until a toothpick inserted into the center comes out clean, about 35 minutes.