Preheat oven to 225 degrees F. Line a large baking ¾ or full baking sheet (or 2 smaller baking sheets) with parchment paper.
In a stand mixer with the whisk attachment, beat egg whites on high until soft peaks form, about 1-2 minutes. While mixer is still running, gradually pour in sugar until fully combined. Continue to beat until stiff and glossy peaks form, which should take about 5-10 minutes. Add in corn starch, lemon juice, and vanilla and mix until just combined.
Add meringue to a piping bag and pipe into nests about 3 inches in diameter, building up the sides a bit to create a nest shape. Alternatively, you can spoon meringue into rough circles and use the back of the spoon to indent and make a well in the center for the filling.
Bake in preheated oven for 1 hour and 10 minutes. Turn oven off but leave meringues in with the door closed for another 30 minutes, which will help the outsides crisp up. Remove from oven and let cool completely.
While meringues cool, make the filling. In a medium size bowl, whip heavy cream together and beat using a hand mixer until thickened and soft peaks form.
In another bowl, beat together nutella, cream cheese, vanilla, and salt until light and fluffy. Fold in whipped cream. Take ¾ cups Cadbury eggs and add to a ziplock bag, then crush with a rolling pin or kitchen mallet until eggs are in small pieces. Fold into whipped cream mixture.
Pipe or spoon nutella and Cadbury cream into the centers of the nests until there is a small mound of filling in the middle. Sprinkle tops of filling with toasted coconut. Add 2-3 chocolate eggs into the center of the nests and serve.
Recipe by Wright Family Table at https://www.wrightfamilytable.com/cadbury-egg-nest-pavlovas/