Beat butter and powdered sugar until smooth using a stand mixer or electric mixer. Cover your mixer with a damp towel to keep powder from covering your surrounding area.

Add vanilla extract, almond extract, and egg to the butter mixture and beat until completely combined with no streaks of egg visible.

In a separate bowl, whisk together flour and baking powder, then gradually stir into the wet ingredients until a soft dough forms that pulls away from the sides of the bowl.

Divide dough into 3 equal portions. Wrap each portion in plastic wrap and refrigerate for 2 hours or overnight. Dough can also be frozen for up to 3 months.

Preheat oven to 350°F. Line cookie sheets with parchment paper or silicone baking mats.

Roll out one portion of chilled dough on a lightly floured surface or silicone mat to exactly ⅓ inch thickness. Cut snowflake shapes and place on prepared cookie sheet.

Place cookie sheet with cut cookies in freezer for 20 minutes before baking. This prevents spreading and helps cookies hold their shape.

Bake for 10-12 minutes depending on size, until cookies are set with edges just barely starting to turn golden. Centers should still appear slightly soft. Let sit on baking sheet for 2 minutes, then transfer to wire rack to cool completely.

For buttercream: Cream shortening and vanilla extract in stand mixer. Gradually alternate adding powdered sugar and milk until thick frosting consistency is reached. The frosting should be thick enough that a spoon stands up in it.

Divide buttercream in half. Keep one half white. Add 1 tablespoon milk to half of the white frosting to thin it, then transfer to piping bag fitted with Wilton No. 3 tip. Transfer remaining thick white frosting to piping bag fitted with Wilton No. 18 tip.

Color remaining buttercream pale blue using Wilton Color Right system (1 drop blue and 0.5 drop brown) or your preferred food coloring. Add 1 tablespoon milk to half of blue frosting to thin it, then transfer to piping bag fitted with No. 3 tip. Transfer remaining thick blue frosting to piping bag fitted with No. 22 tip.

Easy decoration method: Pipe thick frosting on cookie and spread with offset spatula. Add sprinkles while frosting is wet.

Moderate decoration method: Pipe snowflake design with thin buttercream and add pearls and sugar decorations, pressing firmly into frosting to ensure they stick.

Advanced decoration method: Pipe shells on snowflake tips with thick frosting using No. 18 or No. 22 tip. Add pearls and sprinkles using tweezers for precise placement.