Preheat oven to 350 F/180C and butter and line with parchment an 8 inch square baking pan.
In a small saucepan, melt the butter. Remove from heat and let it cool to room temperature.
In a bowl, whisk together the flour, ground cinnamon, salt, and baking soda.
In the bowl of your stand mixer (or with a hand mixer), beat the eggs and brown sugar until light and frothy. Beat in the vanilla and then the melted butter.
Scrape down the sides of the bowl then, on low speed, beat in the flour mixture until incorporated. Fold in the chopped nuts.
Pour the batter into the prepared pan, smooth the top. Add the cinnamon sugar on top of the batter and swirl using a skewer.
Bake for about 30 - 35 mins, or until the top of the bars are dry, golden brown, and a toothpick inserted in the center comes out with a few moist crumbs.
For the glaze combine all the ingredients in a small saucepan on low heat until mixed well and thick.
Remove from the blondies from the oven and place on a wire rack. Let the blondies cool completely before topping with the glaze and chopped pecans.