Melt the butter, and place in the fridge to cool down.
Preheat oven to 375 degrees.
Zest your satsuma into the mixing bowl of a stand mixer.
Add the vanilla and eggs to the mixing bowl. Mix for 5 minutes on high with the whisk attachment.
Lower the mixer speed and slowly add the powdered sugar. Mix on high for another 5 minutes.
Combine the dry ingredients (flour, vital wheat gluten, and baking powder), and add to the egg and sugar mixture slowly, about 1/4 cup at a time. Mix on low until just incorporated. The mixture should now be thick and fluffy looking.
Add the melted/cooled butter, and mix on low until just incorporated. Don't go overboard scraping the bowl out with a spatula. Set the butter bowl aside cause you're going to use it later.
Use a pastry brush, and spread some of the melted butter left in the bowl in the molds. Then, sprinkle a bit of flour over the tray.
Spoon a scant tablespoon of batter into each mold. To get the batter spread out, I use an ancient French technique called "Le Finger.," i.e., just push it down with your pointer finger.
Bake for 10 minutes. Let sit in the molds for one minute, and then remove and let cool on a baking rack.
Topping
Melt chocolate chips and coconut oil in the microwave. Stir. every 30 seconds until fully combined.
Dip one side in the chocolate, and lay on a tray lined with parchment. Put the tray in the freezer for 10 minutes to allow the chocolate to set.
Store in an air-tight container at room temperature if your kitchen is cool. If your kitchen is on the warmer side, please store in the fridge.
Notes
Based off of this allrecipes submission.If you want to use regular all-purpose flour, you won't need the vital wheat gluten.