Preheat and Prepare: First, preheat your oven to 375°F (190°C). Next, lightly grease a donut pan to prevent sticking.
Mix Dry Ingredients: In a large bowl, sift together flour, cocoa powder, granulated sugar, baking powder, and salt. Then, set aside.
Combine Wet Ingredients: Meanwhile, in another bowl, whisk the eggs, milk, melted butter, and vanilla extract until smooth. Next, gradually stir the wet ingredients into the dry ingredients, mixing until just combined. Do not overmix, as you want the dough to remain light.
Fill the Donut Pan: Carefully spoon the batter into the prepared donut pan, filling each mold about 3/4 full. Then, place the pan in the oven and bake for 8-10 minutes, or until a toothpick inserted into a donut comes out clean.
Prepare the Chocolate Glaze: While the donuts are baking, combine the chocolate chips, butter, and heavy cream in a microwave-safe bowl. Microwave in 20-second intervals, stirring between each, until the mixture is smooth and glossy. Next, stir in the powdered sugar until fully incorporated.
Glaze and Serve: Once baked, allow the donuts to cool for 5 minutes in the pan, then transfer them to a wire rack. While the donuts are still warm, dip each one into the chocolate glaze, ensuring they are evenly coated. Finally, add a pinch of sea salt or a few sprinkles on top if desired.