In a frying pan, brown butter over medium heat, stirring constantly until butter turns an amber color. Remove from heat as soon as the butter starts to brown.
Pour browned butter and brown bits into a medium bowl to cool for 15 minutes.
Beat brown sugar, granulated sugar, egg, egg yolk, vanilla and sour cream with the browned butter until combined.
In a medium bowl, whisk flour, baking soda and salt together.
Gradually add the dry ingredients into the wet ingredients. Beat on low until combined, and add a few drops of blue food coloring to obtain the desired color.
Stir in chocolate chips and white chocolate chips. Wrap in plastic wrap and chill dough for 1 hour.
Preheat the oven to 350 degrees.
Using a 1-inch cookie scoop, roll cookie dough and place on an ungreased baking sheet(s).
Top each cookie with mini chocolate candies and coarsely chopped Oreo pieces.
Bake cookies for 10-11 minutes until edges start to brown.
Remove from the oven and let sit on a cookie sheet for 5 minutes, then place on a wire rack to cool.