Pour cream into a small pot and heat until simmering over medium heat. Remove from heat and add chocolate. Stir until smooth. Set in the refrigerator until ready to use.
Preheat oven to 350 degrees F and adjust rack to middle position. Butter each cup of a 12-cup muffin tin. Place butter and sugar in the bowl of a standing mixer with beater attached. Beat butter and sugar until blended, about 1 minute. Turn mixer to low and add vanilla and eggs. Scrape the bowl with a spatula. In a separate large bowl whisk together arrowroot, oat flour, sorghum, rice flour, baking powder and gelatin. Turn the mixer on low and add 1/3 of flour mixture followed by 1/3 of buttermilk. Repeat until all ingredients are added and mix until just incorporated. Turn mixer off and stir batter a few times with a spatula. Using a spoon, fill each muffin cup half way. Top with a large dollop of chocolate mixture. Cover each muffin with remaining batter. Bake for 25-30 minutes until golden brown.
Combine coconut sugar and cinnamon in a small bowl. When muffins are cool enough to handle, brush tops and sides with butter and then roll in the sugar mixture. Best eaten when they’re still a little bit warm.