Preheat: Preheat oven to 350°F (175°C). Line cupcake pan with liners.
Mix dry: In a large bowl, stir together sugar, cake flour, baking powder, baking soda, and salt.
Beat in butter: Add softened butter and beat slowly until mixture resembles damp sand, about 3 minutes.
Combine wet: In a separate bowl, whisk together sour cream, eggs, oil, and vanilla.
Combine: Add wet ingredients to dry and whisk until just combined.
Add milk: Add milk and whisk until smooth and lump free. Batter will be thin.
Fill and bake: Fill liners ⅔ full. Bake 14-16 minutes until toothpick comes out clean. Cool completely.
Make syrup: In a small saucepan, combine water and sugar. Bring to a boil and cook until syrup is completely clear.
Whip egg whites: In stand mixer with whisk, whip egg whites to stiff peaks.
Add syrup: With mixer on high, carefully pour hot syrup down side of bowl into egg whites. Whip until mixture cools completely to room temperature, about 10 minutes.
Add butter: Switch to paddle attachment. On low, add butter slices one at a time until incorporated.
Whip: Increase speed to high and whip until frosting is thick and smooth. It will look curdled first, keep whipping.
Flavor and color: On low, add vanilla and yellow gel coloring. Whip until smooth. For extra-smooth frosting, let mixer run on low for 5 minutes.
Make feet and beaks: Melt orange candy melts with shortening in 10-second increments. Transfer to piping bag and pipe feet and beak shapes onto parchment. Let set until firm.
Pipe chicks: Fit piping bag with large round tip. Pipe large dollop on each cupcake for body, then smaller dollop on top for head.
Add faces: Immediately press two black nonpareils into head for eyes. Gently press orange beak below eyes. Press two feet into bottom of body.
Serve: Repeat with all cupcakes. Serve and enjoy!