Preheat oven to 350 degrees Fahrenheit.
In a bowl, whisk together flour, baking powder, salt, cinnamon and nutmeg. Set aside.
In the bowl of a stand mixer, cream together brown sugar and unsalted butter, approximately 4 minutes.
Add in the eggs and vanilla.
Beat together and scrape down sides of the bowl. Gradually add in the flour mixture while beating on low.
Mix until the flour is incorporated.
Pour batter into a greased 9x13 inch baking pan. Spread evenly with a spatula.
n a small bowl, mix together granulated sugar and ground cinnamon.
Sprinkle over the top of the batter.
Bake for 25-30 minutes or when the top of the blondies gently spring back when being touched lightly.
Cool completely before cutting. Keep fresh in an airtight container.