Step 1

Preheat oven to 350F. Line an 8-by-8-inch baking pan with aluminum foil, spray with cooking spray; set aside.

Step 2

To a large, microwave-safe bowl add the butter and heat to melt, about 1 minute on high power.

Step 3

Wait momentarily before adding the egg so you don’t scramble it. Add the egg, brown sugar, peanut butter, vanilla, and whisk until smooth.

Step 4

Add the flour, salt, and stir until just combined, don’t overmix.

Step 5

Add the chocolate chips and stir to combine.

Step 6

Turn batter out into prepared pan, smoothing the top lightly with a spatula. Bake for about 20 minutes, or until top is set in center and done. A toothpick inserted in the center should come out clean, or with a few moist crumbs, but no batter. Blondies firm up as they cool.

Step 7

After blondies are out of the oven, add the Reese's hearts, evenly spaced in rows and columns, 3-by-Lightly press them down so they adhere. The chocolate will start melting and to avoid it from melting too much because you want the heart shape to stay intact, place the pan in the fridge for about 10 minutes and then return pan to counter to cool completely before slicing and serving. Blondies will keep airtight at room temp for up to 1 week.