Preheat the oven to 350° F (180° C). Line the bottom and sides of an 8-x-8-inch (20-x-20-cm) square baking pan with aluminum foil or parchment paper, leaving enough overhang on all sides of the baking pan to allow for easy removal at the end. Set aside.
In a medium bowl, stir together the flour, cornstarch, and salt. Set aside.
Using an electric hand mixer or a stand mixer, beat the butter, granulated sugar, and brown sugar on medium speed until smooth and creamy, 3 to 4 minutes. Scrape down the sides and bottom of the bowl as needed. Add the evaporated milk and vanilla; mix until incorporated, about 1 minute.
Reduce the speed to low and gradually beat in flour mixture, mix until combined. Be careful not to overmix; the batter will be thick. Stir in the Coconut, and chocolate eggs, mix until evenly distributed.
Spread the dough in an even layer at the bottom of the prepared pan. Gently press additional chopped mini eggs on top of the blondie batter.
Bake for 35 - 40 minutes, or until a toothpick inserted in the center comes out with just a few moist crumbs attached. It’s super important NOT TO OVER-BAKE these blondies. The blondies may appear very soft, but they will set up as they cool.
Transfer the pan to a wire rack and cool completely, about 4 hours, before cutting.
Lift the foil out of the pan using the sides' overhang and cut it into bars.