In a small saucepan, combine sugar, water, maple syrup, and salt.
Place over medium heat, whisking until the sugar fully dissolves.
Sift in the cacao powder and whisk continuously until smooth and glossy, about 3–5 minutes. The sauce should slightly thicken and coat the back of a spoon.
Remove from heat and stir in the vanilla extract and peppermint extract.
Use in any recipe right away, or let the sauce cool completely before transferring to a glass jar or squeeze bottle and storing in the refrigerator.
Store in the fridge for up to 3 weeks.