Mexican Chocolate Donuts

Name: Mexican Chocolate Donuts
Prep time: 15 min
Cook time: 7 min
Total time: 22 min
Cuisine: Mexican
Ingredients: 1 cup milk; 2 Mexican chocolate bars, 3 ounces each (cut into large chunks); 1 1/4 cup all-purpose flour; 2 tablespoons sugar; 2 teaspoons baking powder; 1 teaspoon baking soda; Pinch of kosher or coarse sea salt; 3 tablespoons melted unsalted butter (plus more for greasing the pan); 1 large egg; Special equipment (optional – Ebleskiver filled pancake pan); Fillings (dulce de leche or cajeta, chocolate and hazelnut spread, jams or preserves); Confectioners' sugar (optional for dusting)