Whisk flour, baking powder, and salt in a bowl and set aside.

Beat butter and sugar until fluffy, about 2 minutes.

Add eggs one at a time, then vanilla, mixing well.

Mix in dry ingredients on low speed just until combined.

Divide dough into three bowls and color one red, one blue, and leave one white.

Wrap each portion in plastic and refrigerate 30 minutes until firm.

Roll each portion into similar-sized rectangles on a floured surface.

Stack red, white, and blue layers and press gently to adhere.

Roll tightly into a log, wrap, and refrigerate at least 2 hours.

Preheat oven to 375°F and line baking sheets with parchment.

Slice dough into ¼-inch rounds and arrange on baking sheets.

Bake 8 to 10 minutes until edges are set.

Cool on the pan briefly, then transfer to a wire rack.