Preheat the oven to 250F and line a large baking sheet with parchment paper or a silpat mat.

Using a handheld or stand mixer, whip the egg whites on medium speed in a large mixing bowl.

Add in the granulated sugar slowly, about 1 tablespoon at a time-- it should take 2-3 minutes to add all of the sugar.

Once all of the sugar has been added, turn the speed to medium-high and beat until stiff peaks form-- another 1-2 minutes.

Pipe the mixture into 3” diameter discs onto the baking sheet and use a spoon to create a well in the center of each meringue.
Bake for 1 hour, or until the meringues are firm and dry but not brown on top.

Turn off the oven and leave them to cool inside-- about 1-2 hours.

While the meringues cool, add the softened butter to the bowl of a stand mixer and beat until it becomes smooth and fluffy. Next, add the powdered sugar and heavy cream and beat on medium speed until the mixture becomes smooth and creamy-- make sure to scrape down the sides a few times.

Transfer the buttercream to a piping bag and pipe it into the center of the meringue nests. Top with a few mini eggs and serve immediately.