Preheat your oven to 350 degrees. Prepare a 9 by 13 pan by spraying with. nonstick spray.Now to assemble the blondie batter. In a medium to large bowl add 1 cup of brown butter and. your brown sugar. Whisk together. Leave the remaining butter for icing in the pan. Once the butter and sugar are combined, add the eggs, vanilla, cinnamon, salt, and whisk all of this together.
Last, add your flour and baking powder and use a wooden spoon or rubber spatula to mix this together.
Pour the apples into the bowl and gently fold them into the batter.
Pour the batter into the 9 by 13 pan and spread it out evenly.
Bake it in the oven for 35 minutes.
Remove it from the oven and let it cool on a cooling rack for at least an hour. I like it to be room temperature before I add the icing.
When you are ready to ice the blondies, mix together the remaining brown butter, powdered sugar, milk and vanilla using a whisk. If your butter solidified, melt is just a bit to make it easier to combine.
Drizzle the icing over the blondies and let it all set up. I often place mine in the refrigerator to help it set up faster.
Once they have completely cooled, cut into squares and serve!
Store leftovers in an airtight container in the fridge. I have stored mine at room temperature and have been fine, but to be safe, store them in the fridge. You can also freeze them for up to 3 months.
If you freeze them, remove them from the container and let them come to room temperature on a plate. I would also recommend icing them after they defrost.