• Preheat the oven to 350 degrees Fahrenheit and line 2-3 baking sheets with parchment paper.
• Whisk together 2 cups all-purpose flour, ½ teaspoon salt, and ½ teaspoon baking powder in a medium bowl. Set aside.
• Use a hand mixer or stand mixer to beat ½ cup softened unsalted butter and ⅔ cup granulated sugar on medium-high speed for 2-3 minutes until light and fluffy. Add 2 egg yolks, 2 tablespoons sour cream, 1 ½ tablespoons vanilla extract, and 1 teaspoon lemon extract and mix until just combined, scraping down the sides and bottom of the bowl as needed.
• Add the flour mixture to the butter mixture and mix until just combined and no streaks of flour remain.
• Split the dough into 2-3 sections and roll them out at a time on a lightly floured surface until they are ¼ inch thick. Use Easter egg cookie cutters to cut out the cookies. Press the scraps together and set them aside to rest for about 5 minutes. Reroll the scraps and cut more cookies until all the dough has been used.
• Place the cookies on the parchment-lined cookie sheets leaving 1 ½ inches between them. Bake for 6-8 minutes. The edges will be just set, and the cookies will be very light in color with very minimal coloring on the bottom.
• Let the cookies cool on the pan for 2 minutes for the shape to set before transferring them to a cooling rack. Store the completely cooled cookies in an airtight container until you are ready to ice them.

Royal Icing

• Use a stand mixer with the whisk attachment or a hand mixer to mix 4 cups sifted powdered sugar and 3 tablespoons meringue powder on low speed in a large bowl.
• Add 1 tablespoon light corn syrup and 8 tablespoons of the 9-12 tablespoons water to the powdered sugar mixture and mix on low until the powdered sugar is mostly moistened, then increase the speed and beat on high speed for 2-3 minutes. The icing should be pretty stiff. Add additional water 1 tablespoon at a time until the icing is about the consistency of soft-serve ice cream and forms soft peaks. Reserve 1 cup of frosting and cover tightly with plastic wrap.
• With the remaining icing, add additional water 1-2 teaspoons at a time until the icing drips back into the bowl and the lines of icing take about 10 seconds to melt back into the icing when the whisk is lifted out of the bowl. This is the thin icing that will be used to fill, or flood, the cookies. Separate into small bowls and tint the icing with your chosen colors. Cover each bowl tightly with plastic wrap when not being used. This icing will dry and crust over very quickly, so keeping it covered is important.
• Separate the reserved thicker icing into bowls and tint the bowls the colors you want to make your eggs. This will be the frosting that is piped around the outside of the cookie to hold the thin icing in the center. Be sure to cover the bowls until ready to use. When ready to ice the cookies, pipe the thicker outline and then flood the center with the thin icing and add the details with thin icing.