Place the cacao buttons into the top of a double boiler and set over medium heat. Remove from the heat as soon as they melt, taking care not to let them boil.
Whisk in the cacao powder and maple syrup. Allow to cool for 15 minutes.
Place the mixture into a small pouring jug and pour a little into each heart mould* so that they are a quarter full. Sprinkle with the macadamias and strawberries and top with more chocolate mixture.
Refrigerate until set, about 2-3 hours, before carefully removing the hearts from the mould.
Store in the fridge or at a cool room temperature in an airtight container.
*We used a silicone chocolate mould with small hearts