Preheat oven to 350°F (180°C). Line baking sheets with parchment paper or silicone baking mats. Set aside.

Add the fruity pebbles to a food processor and crush into crumbs. You want to end up with 1 cup of crumbs.

Combine the fruity pebbles crumbs, flour, baking soda, and salt in a medium-sized bowl and set aside.

Cream the butter and sugar together in a large mixer bowl on medium speed until light in color and fluffy, 2-3 minutes.

Add the egg and egg yolk and mix until well combined.

Add the vanilla extract and mix until well combined.

Add the dry ingredients and mix until the dough is well combined. Be careful not to over-mix.

Divide the cookie dough into 8 even balls of about 5-6 tablespoons (about 105g) of cookie dough per ball.

Bake the cookies for 10-15 minutes or until the cookies are no longer glossy and are just about to brown on the edges.

Allow the cookies to cool for 5-10 minutes, then move to a cooling rack to cool completely.

To add the glaze, combine the powdered sugar and milk in a small bowl. Add the fruity pebbles to another small bowl.

Working with one cookie at a time, dip each cookie into the glaze and let the excess drip off, then press the cookie into the fruity pebbles. Set cookies aside to dry, then serve.