Combine the agave and cream in a large saucepan (use one bigger than you think you will need) and bring to a boil. Let boil for 5 minutes, stirring occasionally. Remove from the heat and whisk in the butter, one tablespoon at a time. Transfer to a bowl or jar and let cool completely. If the caramel gets too thick to work with, just heat it slightly.

Combine the coconut sugar with the egg whites in a heatproof bowl of a stand mixer and set over a pan of simmering water; whisk by hand until the mixture is warm and the sugar has dissolved, 2 -3 minutes.

Attach the mixing bowl to the stand mixer fitted with a whisk attachment and beat, starting on low then increasing the speed to medium-high, until the mixture is thick, fluffy and glossy and completely cool, about 6 minutes. Reduce the speed to medium-low and add the butter, 1 tablespoon at a time, beating well after each addition. Add the vanilla and caramel and beat on medium high until the caramel is fully incorporated. Remove the bowl from the mixture and stir the frosting vigorously with a spatula to knock out some of the air and make sure all the caramel is fully mixed in. Let sit at room temperature if using the same day.

Preheat oven to 350 degrees. Line a standard muffin tin with paper liners.

Combine the flour, baking powder and salt in a mixing bowl and whisk. In another mixing bowl, whisk together the coconut sugar with the egg, milk, vanilla and oil. Add the flour mixture to the wet ingredients and whisk until smooth and starting to thicken slightly. Divide the batter among the prepared muffin tins and bake for 18 – 22 minutes or until they are golden brown and puffed, the tops springing back slightly when pressed, and a toothpick inserted into the center comes out clean. Let cool in the pan for 5 minutes, then remove to a wire rack to finish cooling.

Once the cupcakes are completely cool, cut a cone shaped piece about an inch in diameter from the top of the cupcakes. Insert your finger into the holes and widen the bottom a bit. Spoon in about 1 teaspoon of the caramel, cut the tip off the cone and place the top over the caramel. Spread or pipe the frosting on top and drizzle with a little bit of caramel.

The cupcakes can be stored in the refrigerator but are best served at room temperature.