In a large mixing bowl, cream together butter and sugar until light and fluffy, about 3-4 minutes.

Add the eggs one at a time, followed by vanilla extract, mixing until smooth.

In a separate bowl, whisk together flour, cream of tartar, baking soda, and salt.

Gradually add the dry ingredients to the wet mixture, folding until just combined.

Stir in the Fruity Pebbles until evenly distributed.

Cover the mixing bowl and refrigerate the dough for at least 30 minutes.

Preheat your oven to 350°F (175°C) and prepare baking sheets with parchment paper.

Scoop out portions of dough onto the lined baking sheets, leaving space between each.

Bake for 10-12 minutes, or until edges are slightly golden; centers should be soft.

Allow cookies to cool for about 5 minutes before transferring to a wire rack.

Melt white chocolate and dip the bottom of each cookie, allowing excess to drizzle off.