Irish stout bread and homemade butter

Name: Irish stout bread and homemade butter
Ingredients: 750ml/1¼ pint double cream (highest fat content possible), at room temperature; 1 tsp sea salt flakes, plus extra if preferred; 1–2 tsp dulse, finely chopped (optional); butter, for greasing; 450g/1lb coarse wholemeal flour; 30g/1oz porridge oats, plus extra for sprinkling; 2 tsp soft dark brown sugar; 110g/3¾oz plain flour; 2 tsp bicarbonate of soda; 1 tsp salt; 300ml/10fl oz buttermilk; 1 tbsp black treacle or molasses; 255ml/9fl oz Irish stout, such as Guinness