Preheat your oven to 350°F. It's essential to start with a properly heated oven to ensure even baking. While the oven warms up, grab a 9×13 glass baking dish and line it with parchment paper. This will make it easy to remove the blondies once they’re baked.
In a mixing bowl, cream together the butter, granulated sugar, and light brown sugar for about 1 to 2 minutes. You’re aiming for a light and fluffy texture here. Don’t be afraid to scrape down the sides of the bowl occasionally to ensure everything is well combined.
Add the eggs, lemon juice, lemon zest, vanilla extract, and lemon extract to the bowl. Beat everything together on medium-high speed for about 3 to 4 minutes. The mixture may look a bit separated at first, but it will come together into a light and fluffy batter.
In a separate bowl, combine the all-purpose flour, baking powder, salt, and cornstarch. This mixture will provide structure and lift to your blondies.
Carefully add the flour mixture to the butter mixture, mixing just until combined. Be cautious not to overmix, as this could result in tough blondies.
Now, gently fold in the diced strawberries until they are evenly distributed throughout the batter. You want to see those beautiful pieces of fruit in every bite!
Spread the batter evenly into the prepared baking dish. Use a spatula to smooth the top, ensuring it’s level for even baking.
Bake the blondies in the preheated oven for about 30 minutes. They are done when a toothpick inserted into the center comes out clean. Keep an eye on them towards the end of the baking time to prevent overbaking.
While your blondies are baking, whisk together the glaze ingredients: powdered sugar and heavy cream. If you want, add a drop or two of red food coloring to give it a cheerful hue.
Once the blondies are out of the oven, let them cool in the baking dish for a few minutes before spreading the glaze over the warm blondies. This will allow the glaze to seep into the blondies, adding extra sweetness.
After glazing, let the blondies cool completely in the pan before slicing them into squares. They’re best enjoyed fresh, but you might find they disappear quickly!