Step 1: Prepare the Marshmallow Filling
In a medium saucepan, combine the granulated sugar, corn syrup, water, and salt.
Heat over medium heat, stirring constantly until the sugar dissolves. Bring the mixture to a boil and cook for 5 minutes, or until it reaches 240°F (115°C) on a candy thermometer.

Step 2: Whip the Marshmallow
While the sugar mixture is cooking, place the egg whites in a large mixing bowl or the bowl of a stand mixer.
Once the syrup reaches 240°F, slowly pour it into the egg whites while the mixer is running on low speed.
Once all the syrup is added, increase the mixer speed to high and beat the mixture for 8-10 minutes, or until stiff peaks form.
Add vanilla extract and beat for another 1-2 minutes.

Step 3: Shape the Marshmallow Eggs
Dust your hands and a work surface with powdered sugar to prevent sticking.
Scoop out portions of the marshmallow mixture and roll them into egg shapes. You can also use an egg mold if you prefer a uniform shape.
Place the shaped marshmallow eggs on a parchment-lined tray and allow them to set for at least 1 hour.

Step 4: Prepare the Chocolate Coating
In a microwave-safe bowl, melt the semi-sweet chocolate chips with vegetable oil (if using) in 30-second intervals, stirring in between, until the chocolate is smooth and fully melted.

Step 5: Coat the Marshmallow Eggs
Dip each marshmallow egg into the melted chocolate, ensuring it’s fully coated.
Return the chocolate-covered eggs to the parchment-lined tray.
If desired, you can sprinkle colored sugar or sprinkles on top for an extra festive touch.

Step 6: Chill and Set
Refrigerate the coated eggs for 30 minutes to 1 hour, or until the chocolate has fully hardened.

Step 7: Serve
Once the chocolate has set, the Marshmallow Easter Eggs are ready to be enjoyed!