Place butter in a small saucepan over medium heat. Cook, swirling occasionally, for about 5 minutes until the butter turns a deep golden amber color and smells nutty. You will see brown bits forming at the bottom. Remove from heat and pour into a heatproof bowl to cool for 10 minutes.
Preheat your oven to 350°F (175°C). Line an 8x8 inch baking pan with parchment paper, leaving an overhang on two sides for easy removal.
Add the golden monk fruit sweetener to the slightly cooled brown butter and whisk until combined. Add the eggs one at a time, whisking well after each. Stir in the vanilla extract.
Add the almond flour, baking powder, and salt to the wet mixture. Stir with a spatula until a thick batter forms with no dry patches remaining.
Fold in the sugar-free chocolate chips. Spread the batter evenly into the prepared pan and smooth the top with the spatula.
Bake for 22 to 25 minutes, until the top is golden and a toothpick inserted in the center comes out with just a few moist crumbs. The edges should be set and slightly pulling away from the pan.
Remove from the oven and immediately sprinkle flaky sea salt over the top. Let the blondies cool completely in the pan before lifting out by the parchment and slicing into 16 squares.