In a large mixing bowl, beat the softened unsalted butter and cream cheese together until smooth and creamy.

Combine granulated sugar and lemon zest in the bowl; mix until light in color and well combined.

Add the egg yolk and vanilla extract, mix until combined; if desired, add gel food coloring.

In a separate bowl, whisk together flour, cornstarch, salt, and baking powder, then gradually add to the wet ingredients.

Set aside a small portion of dough for coloring; mix in orange gel food coloring.

Scoop out yellow dough, roll into balls, and flatten each ball on a lined baking sheet.

Roll small balls of orange dough for feet and beaks; press them onto the cookies.

Shape remaining yellow dough into wings and attach; add sprinkles for eyes.

Chill the shaped cookies in the refrigerator for 15-30 minutes, then preheat the oven to 350°F (175°C).

Bake in the preheated oven for 15-17 minutes; allow to cool on the baking sheet before transferring to a wire rack.