Preheat your oven to 350°F and line an 8x8 inch glass baking dish with parchment paper.
In a large mixing bowl, whisk together the butter, granulated sugar, and powdered sugar for 1-2 minutes, or until fully combined.
Once the butter and sugars are combined, whisk in the eggs for an additional 1-2 minutes. Add the lemon juice, lemon zest, and vanilla extract. Mix again until the batter is smooth.
Slowly whisk in the flour until no dry clumps of flour remain unincorporated in the blondie batter.
Spread your batter out in the baking dish and bake for 20 minutes, or until the edges begin to brown.
Allow the blondies to cool on the counter while you prepare the lemon glaze by whisking together the powdered sugar, lemon zest, water, and lemon juice in a small bowl until smooth and homogenous.
Spread the glaze over the top of your blondies and then transfer the blondies to the fridge. Allow them to cool in the fridge for 45 minutes.
Slice, serve, and enjoy!