3 ounces (2 full-size bars) Hershey’s Milk Chocolate Bar, chopped**
Fleur de sel or other flaky sea salt, for sprinkling***
Preheat oven to 350ºF and line an 8” square pan with parchment paper or foil. If using parchment, cut the parchment to 8” wide by about 16” long so that you have overhang on two opposite sides of the pan. Spray the exposed sides of the pan with cooking spray. If using foil, spray the entire surface of the foil with cooking spray.
In a small mixing bowl, whisk together the flour, cornstarch, baking soda, and salt.
In the bowl of a stand mixer fitted with the paddle attachment (or using a bowl and handheld electric mixer), beat the butter until smooth and creamy. Add the brown sugar and beat into the butter until fully combined, wiping down the bowl and beater as needed. Add the egg and vanilla extract and beat in until incorporated.
Add half of the dry ingredients to the wet and mix in on low speed just until almost fully incorporated. Add the remaining flour and continue to mix just until all ingredients are evenly combined, scraping down the bowl and beater as necessary.
Toss the M&M’s and chopped Hershey bar together. Add 3/4 of the mixture to the dough and fold in with a spatula just until evenly dispersed.
Transfer the dough to the prepared pan and use hands to press into an even layer that covers the entire bottom surface. Using a flat spatula or bench scraper, press down on the dough to flatten it out. Sprinkle the remaining candy mixture over the surface and press in lightly with your hands. Sprinkle with fleur de sel or sea salt.
Bake blondies in preheated oven for 25-30 minutes, until edges are pulling away from the sides of the pan and the top is golden-brown. A toothpick inserted into the center should come out clean.
Place pan on a wire rack and allow blondies to cool to room temperature before lifting from pan and slicing into 12 bars.
These are best served fresh, but can be stored in an airtight container at room temperature for up to a couple days.
*To quickly bring eggs to room temperature, place in a bowl filled with warm water to cover. Let sit for 5-10 minutes before using.
**It might go without saying, but you can feel free to switch these out with about 1 cup of whatever candy you have on hand.
***Skip the salt if you’re not typically a fan of salted desserts!