In a chilled mixing bowl, whip heavy cream with an electric mixer until stiff peaks form, about 3-5 minutes. Transfer to the fridge to keep cool.

Brush the rims of glasses with maple syrup and dip in black sanding sugar. Place glasses in the freezer for 10 minutes.

In a blender, combine vanilla ice cream, milk, black cocoa powder, maple syrup, and vanilla extract. Blend on high for 30-60 seconds until smooth.

Taste the milkshake and adjust the flavor with more black cocoa if desired, blending for an additional 10-15 seconds.

Pour the milkshake into prepared glasses, top with whipped cream and sprinkle with black sanding sugar. Serve immediately.