Add the agar powder into a medium saucepan and pour 3/4 cup of the water over it, and set aside for 10 minutes without stirring or heating.
Bring the liquid to a boil over medium heat, stirring a few times. Reduce the heat to law. Cover the saucepan and simmer for 5 to 6 minutes, stiring a few times to release any bits of agar that may be stuck on teh bottom of the pan. Check that the agar is fully dissolved.
Whisk in the coconut milk, maple syrup, and salt into the agar mixture and simmer for 2 minutes. Add the sugar and simmer for about 1 minute until dissolved. Add the cocoa powder slowly, whisking constantly until it is dissolved. Simmer for another 2 to 3 minutes. Make sure you stir the bottom so it doesn't burn. Add the chocolate and stir until melted.
In a small cup, dissolve the arrowroot with the remaining 2 tablespoons of water. Whisk constantly and add this slurry to the simmering chocolate liquid. Cook only until a full boil is reached. The mixture will feel thick almost immediately. Remove the saucepan from the heat and add the vanilla extract. Stir frequently until the mixture becomes lukewarm.
Pour the chocolate cream into a 9 inch by 9 inch glass baking dish or other shallow dish and let cool to room temperature. Refrigerate for 1 to 2 hours until the cream is firm.
Spoon the mixture into a food processor and pulse a few times until creamy. It will be similar to a chocolate pudding.
Transfer into a pipping bag with a pipping tip (I used the Wilton 1M for these cupcakes). Carefully top each cooled cupcakes with the frosting and an upside down raspberry.