Heat oven to 400 degrees F.
Separate the yolks on two eggs. Set the whites aside.
Mix the yolks, other 3 whole eggs, sugar, and vanilla extract together over medium speed for 4-5 minutes.
Melt the ¾ cup butter, then add to the egg mixture, along with food coloring.
Mix for 1 minute.
In a separate bowl, mix together the dry ingredients: flour, cornstarch, 2 tablespoons cocoa powder (reserve the last tablespoon for later), baking powder, and salt.
Add to mixer and mix until just combined and all ingredients are wet.
Take the 1 tablespoon melted butter and brush the cavities of the madeleine pan with a rubber pastry brush (if using a 12 cavity pan, reserve half of this butter for the second batch). Lightly sprinkle the buttered cavities with half of the reserved cocoa powder. Use a tablespoon to fill the cavities about ¾ of the way. Do NOT fill all of the way.
Bake for 10 minutes, and 9 minutes for the second batch.
Remove to a wire pan in between batches and let cool.
Once cool, melt the candy melts according to package directions.
Use a spoon to spread the melted candy melts on the top part of each madeleine, spraying with glitter or adding sprinkles before the candy sets.
Let dry for a few minutes and enjoy. Keeps in an airtight container for about 3 days.