Measure out the cold 115 grams Unsalted Butter, cube about 1cm, (⅓") & place back in the fridge till ready to make.
Paper line 2 large baking trays/baking sheets with baking/parchment paper (& grease in place if there is no lip).
Measure out the other ingredients & process 150 grams Porridge Oats (Rolled Oats/Old Fashioned Oats) to a finer consistency. Alternatively use fine oats. **Please see notes below on cup amounts).
In a large mixing bowl, mix together all the dry ingredients - 150 grams Wholemeal Flour (wholewheat flour), ¼ tsp Bicarbonate Of Soda, (Baking Soda), ¼ tsp Salt, 29 grams Desiccated Coconut (if using) & the processed oats.
Remove the cold cubed butter from the fridge now, add to the dry ingredients & toss to coat. Using a pastry cutter/pastry blender, food processor, your fingertips or 2 butterknives to 'cut the butter' into the dry mix, till a 'breadcrumb consistency'. (See the video or step-by-step instructions for more details).
Mix in the 38 grams Light Brown Sugar (& 29 grams Desiccated Coconut if using - but remember to process or chop roughly if using shredded coconut - see notes).
Gradually add 2-3 tbsp Milk until the dough comes together into a manageable & not sticky mass, kneading to bring together, or using the food processor until it comes away clean from the sides of the processor bowl. Form into a disc, wrap in cling film/plastic wrap & chill for 30 minutes (or freeze for 15 minutes).