If making whipped cream, add heavy cream to a bowl and whip at medium speed until it begins to thicken. Increase to high speed and continue whipping until peaks stand up straight. Place in the fridge while making the milkshake.

For the rim, pour black sanding sugar into a shallow bowl. Brush the rim of a glass with maple syrup and dip it into the sanding sugar. Tap off excess sugar and place in the freezer for a few minutes.

Add vanilla ice cream, milk, black cocoa powder, maple syrup, and vanilla extract to a blender, and blend until fully combined without lumps. Adjust thickness with additional milk if necessary.

Top with whipped cream and add sprinkles if desired.