These are delicious as-is, with or without frosting, and amazing with the addition of chocolate chips.
From Smitten Kitchen
8 Tablespoons butter (1 stick), melted
1 cup light brown sugar
1 large egg
1 teaspoon vanilla extract
1 cup all-purpose flour
Preheat oven to 350 degrees.
Prepare an 8x8 pan by lining with parchment or buttering.
Beat melted butter and brown sugar until smooth. Add egg and vanilla.
Mix in flour and salt until just combined.
Pour into pan and bake for 20-25 minutes, until set.
Allow to cool before slicing.
1 1/2 cups powdered sugar
1 stick butter, softened
1/2 teaspoon vanilla extract
Beat butter until fluffy and smooth.
Add in sugar and beat well.
Add vanilla and mix until smooth and spreadable. If necessary, add a splash of milk to thin.
Spread frosting over cooled blondies.