Preheat oven to 180º.
Line a loaf tin with baking parchment.
In a small bowl, whisk the flours, baking soda, baking soda and salt. Reserve.
In a large bowl, whisk together the clarified butter and sugars, followed by the mashed banana and vanilla extract.
Add sifted flours, chopped walnuts and chocolate chips into the wet mix.
Mix gently just until combined. Do not overmix.
Pour the batter into the prepared loaf pan.
Top with walnut halves and chocolate chips.
Bake at 180Cº for approximately 35-40 minutes, or until the tester comes out clean.
Cool in tin for 30 minutes at least, then cool on rack.
Serve sliced warm or at room temperature.
Note: Loosely tent the top with a sheet of aluminium foil in the last 10-15 minutes if the top is over browning.