Preheat oven at 350 degrees F. In a large bowl, beat softened butter until smooth and fluffy. Add sugar and beat very smooth and fluffy, approximately 5 minutes.

In a separate bowl, whisk your eggs. Whisk eggs into the butter sugar mixture at 1 tbsp at a time for a very soft cake.

In a separate large bowl, sift cake flour, salt and baking powder. Add ⅓ of the dry ingredients into the wet ingredients and using a spatula, fold the dry into the wet but do not over fold. Repeat until you have folded in all the dry ingredients.

In another bowl, sift matcha powder into the oat milk. Whisk until smooth. Then pour ⅓ of the cake batter into the matcha liquid and mix until the batter is coloured green.

Into your original cake batter bowl, add dollops of the green cake batter. Using your spatula, fold from the bottom 3 times to get the marble effect. Then pour into a greased loaf pan. Smooth out the top of your cake.