Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a large mixing bowl, cream the butter and sugar until light and fluffy, about 2-3 minutes.

Add the eggs and vanilla extract, mixing until fully combined.

In a separate bowl, whisk together the flour, baking soda, cream of tartar, and salt. Gradually mix this into the wet ingredients.

Gently fold in the sprinkles until evenly distributed.

Divide the dough into four portions; dye three with gel colors (pink, royal blue, violet) and leave one uncolored.

Lightly swirl the colored doughs together for a tie-dye effect without overmixing.

Scoop the dough into balls, rolling them in sugar or sprinkles, and place them on the prepared baking sheet with space in between.

Bake for 10-12 minutes until edges are golden but centers remain soft.

Allow cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.