Place rack in centre of oven. Preheat oven to 180°C (350°F). Grease a 20 cm (8 in.) square pan and line the bottom with parchment paper, letting the paper overhang on two sides.
In a bowl, mix the flour, cocoa powder and salt. Set aside.
In a separate bowl, using a double boiler or microwave, melt the chocolate with the coconut oil and almond butter. Mix and let cool.
Using an electric mixer, beat the eggs, sugar and vanilla extract until smooth and well-combined. Add the chocolate mixture, the banana and the dry ingredients and mix until combined. Pour into pan. Top with the almonds.
Bake for 25 minutes or until a toothpick inserted into the centre of the cake comes out mostly clean.
Let cool in pan. Remove from pan and cut into 16 squares.