Combine Dry Ingredients: In a stand mixer, combine flour, baking powder, salt, powdered sugar, and granulated sugar. Mix on medium until well blended.

Add Butter: Gradually add the butter to the dry ingredients and continue mixing. Add vanilla extract and continue mixing until the dough forms a ball.

Divide Dough: Remove the dough and divide it into two equal parts. Return one portion to the mixer and add red food coloring. Mix until the dough is completely red.

Roll Out Dough: Roll out each portion of dough between two sheets of wax paper to about 11 x 9 inches and ¼ inch thick. Chill both dough layers in the fridge for at least 1 hour.

Combine Dough Layers: After chilling, remove the wax paper from the dough layers. Brush the uncolored dough lightly with water and stack the colored dough on top. Press the edges lightly to seal.

Create Swirl: Roll the dough up jelly-roll style from the long side, then gently roll it in colored sprinkles. Wrap in plastic wrap and chill for a few hours or freeze for up to 3 months.

Slice and Bake: Slice dough into ¼-inch slices and place on parchment-lined baking sheets. Bake in a preheated oven at 350°F (175°C) for 10-12 minutes, until the edges are golden brown. Let cool for 5 minutes before transferring to a wire rack.