In a mixing bowl, whisk together all-purpose flour, baking powder, and salt until well combined.

In a separate bowl, beat softened unsalted butter until creamy. Gradually add granulated sugar and continue mixing until light and fluffy.

Add in eggs and vanilla extract, mixing until just combined.

Slowly add the dry mixture to the wet ingredients, mixing on low speed until just combined and a soft dough forms.

Divide the prepared dough into three equal portions. Leave one portion plain for the white layer.

Use red gel food coloring to tint one portion, adding gradually until desired shade.

In the third portion, mix in blue gel food coloring, following the same method.

Shape each colored dough portion into flat rectangles, about half an inch thick. Wrap in plastic wrap and refrigerate for 30 minutes.

Once chilled, roll out each portion between sheets of parchment paper into rectangles about ¼ inch thick.

Begin with the plain dough, followed by the red and then the blue layers on top.

Starting from the short end of the stacked dough, roll tightly into a log, maintaining even pressure.

Wrap the log in plastic wrap and refrigerate for at least 2 hours, or overnight.

Preheat your oven to 375°F (190°C). Slice the dough log into ¼-inch rounds.

Place rounds on a baking sheet lined with parchment paper and bake for 8-10 minutes.

Let cookies cool on the baking sheet for a few minutes before transferring to a wire rack.