Adjust oven rack to middle position and heat oven to 350 degrees.

Make foil sling for 13 by 9-inch baking pan by folding 2 long sheets of aluminum foil; first sheet should be 13 inches wide and second sheet should be 9 inches wide.

Lay sheets of foil in pan perpendicular to each other, with extra foil hanging over edges of pan.

Push foil into corners and up sides of pan, smoothing foil flush to pan.

Lightly spray foil with vegetable oil spray.

Whisk flour, table salt, and baking powder together in medium bowl.

Heat butter in 10-inch skillet over medium-high heat until melted, about 2 minutes.

Continue to cook, swirling skillet and stirring constantly with rubber spatula, until butter is dark golden brown and has nutty aroma, 1 to 3 minutes longer.

Remove skillet from heat and transfer browned butter to large heatproof bowl.

Add sugar to hot butter and whisk until combined.

Add eggs, corn syrup, and vanilla and whisk until smooth.

Using rubber spatula, stir in flour mixture until fully incorporated.

Stir in pecans and chocolate chips.

Transfer batter to prepared pan; using spatula, spread batter into corners of pan and smooth surface.

Sprinkle with sea salt, if using.

Bake until top is deep golden brown and springs back when lightly pressed, 35 to 40 minutes, rotating pan halfway through baking.

Let blondies cool completely in pan on wire rack, about 2 hours.

Using foil overhang, lift blondies out of pan and transfer to cutting board.

Remove foil.

Cut into 24 bars.