1-First, preheat the oven to 350°F and grease or line an 8×8 inch baking dish. This ensures easy release after baking and helps achieve that perfect moist texture. Cream the softened butter and granulated sugar together until light and fluffy, then beat in the egg and vanilla extract until smooth.

2-Next, in a separate bowl, whisk together the flour, baking powder, and salt, then gradually mix the dry ingredients into the wet mixture until just combined. This step is crucial to avoid overmixing and keep the dough soft.

3-Once mixed, fold in the thawed lemonade concentrate and lemon zest to add that tangy twist. Spread the dough evenly in the prepared baking dish and smooth the top with a spatula. Bake for 20 to 25 minutes until the edges are golden and the center is set but still moist, allowing for a tender finish.

4-After baking, let it cool completely, then dust with powdered sugar and cut into 9 squares.