Whisk together water, maple syrup, cocoa powder, vanilla extract, cinnamon, cayenne pepper, and salt in a medium saucepan over medium-high heat. Bring to a boil.
Reduce heat to medium-low and slowly whisk in a little a2 Milk®. Stir to completely incorporate the milk; then whisk in remaining milk. Stir to completely combine.
Heat for about 5-8 minutes until milk is hot but not boiling. Pour into mugs and enjoy!