Cream the unsalted butter and powdered sugar in a large mixing bowl using a hand mixer until light and fluffy, about 3-4 minutes. Beat in the eggs and milk until smooth. Gradually add flour, salt, and extracts, mixing just until a soft dough forms.

Divide the dough in half. Tint one half with purple gel food coloring and leave the other plain. Divide the plain dough, color one half with black gel and keep the other uncolored.

Roll the black dough into a rectangle (6x12 inches) and do the same with the white dough. Stack the black on top of the white, gently rolling them together.

Roll the purple dough into a rectangle (6x12 inches), sprinkle with purple sprinkles, press lightly, and roll tightly into a log.

Position the purple log at the short end of the black-and-white dough layers and roll them over the purple log, sealing the edges completely.

Wrap the spiral log tightly in plastic wrap and refrigerate for at least 1 hour. Roll in black or chocolate sprinkles after chilling.

Preheat the oven to 375°F (190°C). Slice the log into ¼-inch rounds and place on baking sheets lined with parchment paper. Top with additional sprinkles.

Bake for 10 minutes or until edges are set and tops are slightly golden. Cool for about 10 minutes on the pan before transferring to a wire rack.