Instructions: Turn the oven on to 300 degrees Fahrenheit 150 degrees Celsius and place parchment paper on a baking sheet. Lightly whisk the egg whites in a dry, clean mixing bowl until frothy. When stiff peaks form, add the granulated sugar and whisk once more. Almond flour and powdered sugar should be sifted together. Mix thoroughly after adding the salt. To combine the dry mixture with the egg whites, gently fold it in. Stir in vanilla extract, blue food coloring, and cream of tartar. Fold the batter until it is smooth and ribbon-like. Spoon the batter into a piping bag fitted with a circular tip. Pipe tiny, evenly spaced circles onto the baking sheet that has been prepared. After removing any air bubbles by tapping the baking sheet against the counter, allow the macarons to rest for approximately 20 minutes, or until a skin forms. Bake for 15 to 18 minutes, or until the macarons are set on top and have risen in the preheated oven. After a few minutes of cooling on the baking sheet, move the macarons to a wire rack to finish cooling. After cooling, fill each macaron with Cadbury Egg Buttercream by sandwiching one macaron shell over the center of a Cadbury Egg. To allow the flavors to meld, store the macarons in the refrigerator in an airtight container for at least 24 hours before serving. Savor your Macarons with Robin's Eggs!