Combine Dry Ingredients: In a medium bowl, sift together the all-purpose flour, baking powder, and salt. Whisk to combine thoroughly. Set aside.

Cream Butter and Sugar: In the bowl of a stand mixer fitted with the paddle attachment (or in a large bowl using a hand mixer), beat the softened butter until smooth and creamy, about 2 minutes.

Add Sugar: Gradually add the granulated sugar to the butter. Continue beating on medium-high speed until the mixture is light and fluffy, about 3 minutes.

Add Eggs and Vanilla: Add the room-temperature eggs one at a time, beating well after each addition until fully incorporated. Stir in the vanilla extract.

Combine Wet and Dry Ingredients: With the mixer on low speed, gradually add the dry ingredients (flour mixture) to the wet ingredients, mixing until just combined. Do not overmix.

Divide and Color Dough: Divide the dough into three equal portions.

Keep the white: Keep the first portion

Color Dough (Red): Return one portion of the dough to the mixing bowl. Add red gel food coloring, a little at a time, and mix on low speed until the dough reaches your desired shade of red. Start with a small amount of food coloring and add more as needed.

Shape and Wrap Red Dough: Shape the red dough into a 4×4-inch square. Wrap it tightly in plastic wrap and refrigerate.

Clean Bowl: Thoroughly clean the mixing bowl and paddle attachment to remove any traces of red food coloring.

Color Dough (Blue): Place the final portion of dough in the clean mixing bowl. Add blue gel food coloring, a little at a time, and mix on low speed until the dough reaches your desired shade of blue.

Shape and Wrap Blue Dough: Shape the blue dough into a 4×4-inch square. Wrap it tightly in plastic wrap and refrigerate.

Shape and Wrap White Dough:

Chill Dough: Refrigerate all three squares of dough (red, white, and blue) for at least 30 minutes. This makes the dough easier to roll out.

Roll Out Dough (One Color at a Time):

• Remove one square of dough (e.g., red) from the refrigerator.
• Place the dough between two sheets of wax paper.
• Roll the dough out into a rectangle about 1/8-inch thick. Aim for a roughly uniform rectangle, but the exact dimensions aren’t critical at this stage.
• Repeat this process with the white and blue dough, rolling each color out separately between sheets of wax paper.

Stack Dough Layers:

• Carefully peel off the top layer of wax paper from the red dough rectangle.
• Peel off the top layer of wax paper from the white dough rectangle.
• Carefully flip the white dough rectangle on top of the red dough rectangle, aligning the edges as best as possible. Peel off the remaining wax paper from the white dough.
• Peel off the top layer of wax paper from the blue dough rectangle.
• Carefully flip the blue dough rectangle on top of the white dough rectangle, aligning the edges. Peel off the remaining wax paper from the blue dough.

Roll Layers Together: Use a rolling pin to very lightly roll over the stacked dough layers, just to help them adhere to each other.

Roll into a Log: Starting at one of the shorter ends of the rectangle, tightly roll the dough into a log.

Wrap and Chill Log: Wrap the log tightly in wax paper, and then wrap it again in plastic wrap. Refrigerate for at least 1 hour.

Prevent Flat Side (Important): After 1 hour, remove the dough log from the refrigerator. Roll it on the counter several times to help maintain its round shape and prevent it from developing a flat side. Alternatively, you can stand the wrapped log upright in a tall glass in the refrigerator.

Chill Again: Return the dough log to the refrigerator and chill for at least 4 more hours, or preferably overnight. The dough must be very firm for slicing.

Preheat Oven and Prepare Baking Sheets: When ready to bake, preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper.

Slice Cookies: Remove the chilled dough log from the refrigerator. Unwrap it. Using a sharp knife, slice the log into 1/4-inch thick rounds.

Arrange on Baking Sheets: Place the cookie rounds on the prepared baking sheets, leaving about 2 inches of space between each cookie.

Bake: Bake for 9-11 minutes, or until the edges are pale golden brown. The cookies will not brown much.

Cool: Let the cookies cool on the baking sheets for a few minutes before transferring them to a wire rack to cool completely.