Preheat the oven to 350°F. Line an 8×8 baking dish with parchment paper or heavy-duty aluminum foil, leaving a bit of overhang on the sides so you can easily lift the blondies out later. Lightly spray the lining with nonstick cooking spray, then set aside.

In a small mixing bowl (2 to 3 cups), whisk together the flour, baking powder, and salt until combined.

Using a stand mixer or a medium mixing bowl (2 to 3 quarts) with a handheld mixer, beat the softened butter on medium-high speed for about 30 seconds to 1 minute, until smooth.

Add the granulated sugar and continue mixing for 1 to 1½ minutes, or until the mixture is light and fluffy.

Reduce the mixer speed to medium-low. Add the room-temperature eggs one at a time, mixing well after each addition.

With the mixer still on medium-low, add the flour mixture and mix just until everything is incorporated.

Stir in the lemon zest and drizzle in the lemon juice, mixing only until combined.

Spoon the batter evenly into the prepared baking dish and gently tap the pan on the counter to release any trapped air bubbles. Bake for 18 to 20 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs. Keep an eye on them starting around the 15-minute mark, as ovens can vary. The blondies should remain pale yellow rather than golden brown. Remove from the oven and let cool in the pan for about 30 minutes, or until fully cooled. Once cooled, prepare the lemon glaze.

In a small mixing bowl (2 to 3 cups), whisk together the powdered sugar, lemon zest, and fresh lemon juice until smooth.

Use a silicone spatula or offset spatula to spread the glaze evenly over the blondies. Let the glaze set before lifting the blondies out of the pan using the parchment or foil overhang. If your kitchen is warm, you can place the pan in the refrigerator briefly before slicing.

Cut into 16 squares using a sharp knife before serving.