Line an 8x8" baking pan with parchment paper or tinfoil, set aside.
In your mixing bowl, cream together the butter and sugar until light and fluffy (about 3 minutes). Add the egg and vanilla and continue to beat until incorporated. Add the flour 1/2 cup at a time, making sure to scrape down the sides of the bowl.
Gently fold in the Oreos and the sprinkles, then transfer the batter to the prepared pan.
Bake for 20-25 minutes, or until the center is set. Remove from oven and let cool. Use the parchment paper to pull the blondies out of the pan, for easy cutting.