Instructions

 Prepare the Eggshells 

1. Using a sharp knife, skewer, or nail scissors, carefully poke a small hole at the top of each egg. Carefully enlarge the hole (about 1/3 -½ inch wide) to allow you to pour out the egg inside. If the egg white and yolk won’t come out, take a wooden skewer and poke inside the egg. (REMEMBER to separate the contents of 2 eggs for the brownie mixture!!!). Save the remaining egg contents for another recipe or scrambled eggs.
2. Rinse the eggshells thoroughly with warm water over the sink. Make saltwater by dissolving 3.5oz. (100g) of salt in about 4 and ¼ cups (1 liter) of water. Soak eggshells in a saltwater solution for 30 minutes. They will have to be filled with saltwater to sink completely. After 30 minutes, rinse the shells again and allow them to dry completely. Lay the eggs, hole side down, on a paper towel to drain completely and dry well.
3. Lightly coat the inside of each shell with oil to prevent sticking. Pour a small amount of oil in each eggshell, rotate to cover the whole inside, and pour out the excess oil.
4. Arrange the egg shells in a muffin pan and use aluminum foil to help them stand upright. during the filling and baking.

 Make the Brownie Batter 

1. Preheat your oven to 350°F (175°C).
2. Melt the butter and add finely chopped chocolate. Stir well until the chocolate is melted and smooth. Set aside to cool slightly.
3. In a mixing bowl, whisk together sugar, 2 eggs, and vanilla extract.
4. Pour in melted chocolate and whisk until smooth.
5. Sift in the cocoa powder, flour, and salt. Stir until just combined—do not overmix.

Fill and Bake 

1. Transfer the brownie batter into a piping bag with a small nozzle tip (or in a zip-top bag with the corner cut off) for easier filling.
2. Carefully pipe the batter into each prepared eggshell, filling about ¾ full.
3. Bake for 15–20 minutes. Some of the brownie batter will overflow the eggshell during the baking process and drip over, but don’t worry, you will clean it after baking.
4. Let them cool for a few minutes. While the eggs are still warm, scrape off any excess of the brownies and use a wet towel to wipe it off, but be careful not to burn yourself with hot egg shells.

Serve and Enjoy! 

1. You can serve it with whole eggshells like real “hard-boiled eggs.”
2. Gently crack the shells like a real egg to reveal the surprise brownie inside!
3. You can also peel off some of the shell to create a cracked effect, making them look even more fun.