1. Preheat your oven to 350°F (175°C) and line a 9×13-inch baking pan with parchment paper, leaving some overhang for easy removal.
2. In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.
3. In a large mixing bowl, cream the butter and sugar until light and fluffy, about 3-4 minutes. This step reminds me of the patience I learned from my abuela, waiting for the perfect creamy consistency.
4. Add the eggs one at a time, mixing well after each addition. Stir in the lemon zest, lemon juice, and vanilla extract until combined.
5. Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Be careful not to overmix — the dough should be soft but not sticky.
6. Spread the dough evenly into the prepared baking pan. Smooth the top with a spatula.
7. Bake for 20-25 minutes, or until the edges are lightly golden and a toothpick inserted into the center comes out clean.
8. Allow the bars to cool in the pan for about 10 minutes, then use the parchment overhang to lift them out and transfer to a wire rack to cool completely.
9. Once cool, dust with powdered sugar if desired, then cut into squares and enjoy!

These bars are best enjoyed fresh but will keep their moist texture for a couple of days if stored properly.