Pre-heat oven to 350 F.
Line an 8 x 8 inch aluminum metal pan with parchment paper, up 2 opposite sides of the pan. (Do not use a glass pan here)
Melt butter completely in a glass microwave safe mixing bowl. (Or melt in a pan if you prefer.)
½ cup Unsalted Butter
Once it's melted add the brown sugar to the butter and stir until fully dissolved and smooth.
1 cup Brown Sugar
Allow the mixture to cool to room temperature and then add the vanilla paste, whole egg and yolk.
1 large egg, 1 large egg yolk, 2 tsp vanilla bean paste
Fold in flour, baking soda, cinnamon, salt and about ½ cup chocolate chips. Mix just until you do not see any dry flour.
½ tsp sea salt, ½ tsp baking soda, ¼ tsp ground cinnamon, 1 cup all-purpose flour (130 grams or 4.6 oz.,-double this amount if doubling the recipe), ¾ cup chocolate chips (mix of semi-sweet or dark with white chips)
Transfer blondie batter to prepared baking dish and disperse evenly in pan. Top with remaining 1/4 chocolate chips.
Bake on the center rack, in the middle for 25-28 minutes. (DO NOT OVERBAKE! Everyone's oven is a little different. Stop baking once sides start pulling away from sides, edges a little brown and center is not too jiggly. Toothpick can come out wet and crumbly but not raw. It will continue to bake in the pan to finish.)
After removing pan from the oven, set on a cooling rack and allow to set up for at least 20 minutes before cutting. Cut into 16 small 2" squares.