S'mores cupcakes

Name: S'mores cupcakes
Prep time: 30 min
Cook time: 2 h 40 min
Total time: 2 h 40 min
Yield: 12 portions
Ingredients: 130 g digestive biscuits; 70 g unsalted butter; 80 g raw sugar; 150 g plain flour; 20 g Dutch cocoa powder; ½ tsp baking powder; 1 tsp bicarbonate of soda; 1 pinch sea salt; 2 eggs; 80 g buttermilk; 50 g vegetable oil; 1 tsp natural vanilla extract; 50 g boiling water; 120 g dark chocolate chips; 80 g dark chocolate chips; 50 g full cream milk; 10 g unsalted butter; ¼ tsp natural vanilla extract; 100 g white sugar; ¼ tsp cream of tartar; 30 g water; 2 egg whites