Preheat oven to 350 °F (175 °C). Line a 9×9‑inch pan with parchment paper, leaving overhang for easy removal.

In a large bowl, stir together melted butter and sugar until well combined.

Add the egg, mixing thoroughly, then stir in the lemon juice. It may not fully incorporate, that’s fine.

Whisk in flour, baking powder, and salt just until combined.

Fold in the diced fresh strawberries gently so you don’t crush them.

Spread the thick batter evenly into the prepared pan.

Bake 30–35 minutes, until edges are golden and a toothpick inserted in center comes out moist but not wet. Avoid over‑baking.

Cool completely on a wire rack before glazing.

Meanwhile, process about 2 large strawberries into puree, strain to yield ~1 Tbsp. Whisk together powdered sugar, strawberry puree (or jam), and lemon juice until smooth and pale pink; adjust sugar or juice for thickness.

Drizzle or spread glaze over cooled bars. Let glaze set before slicing into squares.