Preheat the oven to 350⁰F and prepare a 10 inch tart pan (or an 8x8 inch square pan in you want regular blondies).
Melt the butter in the microwave and let cool slightly. If desired, you could brown the butter to add another nutty flavor to the cookie. I’m a huge fan of browned butter, but I decided to let the malt flavor sing.
Whisk the brown sugar with the butter until mixed. Add the egg and vanilla. Whisk until smooth.
Add the flour, baking powder, salt, and milk powder and stir until combined. It will seem like there is not enough liquid in the mix to absorb all of the dry ingredients, but keep going! It will incorporate with some effort.
Add in the sprinkles and fold until combined. Into your prepared pan, press the dough flat to cover all of the surface area.
Cut the Toblerone pieces into a rough chop and sprinkle over the top of the tart. Press slightly on the bigger pieces to ensure it bakes into the tart.
Bake the tart for about 23-25 minutes or until the center is set. Let cool before cutting it into 8 pieces.