Banana Spice Cake

• 1 packet butter buds liquified
• 200 gr sugar
• 190 gr mashed ripe bananas
• 160 gr sifted wheat flour (whole)
• 130 gr sifted all-purpose flour
• 120 gr liquid egg substitute
• 160 ml no-salt-added buttermilk
• 16 gr walnuts (chopped optional)
• 6 gr baking powder
• 6 gr baking soda