01 - Preheat the oven to 350°F (175°C). Line an 8x8-inch (20x20 cm) baking pan with parchment paper, leaving some overhang for easy removal.
02 - In a large bowl, whisk together the melted butter and granulated sugar until smooth. Add the eggs, vanilla extract, lemon zest, and lemon juice. Whisk until well combined.
03 - In a separate bowl, whisk together the flour, baking powder, and salt.
04 - Gradually fold the dry ingredients into the wet mixture until just incorporated. Do not overmix.
05 - Gently fold in the raspberries, being careful not to crush them too much.
06 - Spread the batter evenly into the prepared pan and smooth the top. Bake for 28–32 minutes, or until the edges are just golden and a toothpick inserted in the center comes out with a few moist crumbs. Do not overbake.
07 - Allow blondies to cool completely in the pan on a wire rack.
08 - Whisk together powdered sugar, lemon juice, and lemon zest until smooth and pourable.
09 - Drizzle the glaze evenly over cooled blondies. Let set for at least 10 minutes, then cut into 16 squares and serve.