01 - Preheat oven to 350°F and line two baking sheets with parchment paper.
02 - Whisk together flour, baking powder, and salt in a medium bowl until well combined.
03 - Beat butter and granulated sugar in a large bowl until light and fluffy, approximately 2-3 minutes.
04 - Mix in egg, vanilla extract, and almond extract until fully incorporated into the butter mixture.
05 - Gradually add flour mixture to wet ingredients, mixing just until dough comes together. Avoid overmixing.
06 - Divide dough evenly into 4-5 bowls. Tint each portion with a different pastel gel food coloring, mixing until color is uniform throughout.
07 - Using a tablespoon or cookie scoop, portion dough into balls. Place 2 inches apart on prepared baking sheets.
08 - Gently flatten each dough ball with your palm to ensure even baking.
09 - Bake for 10-12 minutes until edges are set but centers remain slightly soft. Remove before overbaking.
10 - Let cookies rest on baking sheets for 5 minutes, then transfer to wire rack to cool entirely before filling.
11 - Beat butter until creamy. Blend in powdered sugar, vanilla, salt, and milk. Continue mixing until smooth and fluffy, adjusting consistency with additional milk if needed.
12 - Pipe or spread buttercream onto the flat side of half the cooled cookies. Top each with a matching cookie to form sandwiches.
13 - Press sprinkles into the exposed buttercream around edges for decorative effect, if desired.