01 - Preheat the oven to 350°F. Grease and line an 8x8-inch baking pan with parchment paper.
02 - In a large mixing bowl, combine melted butter, granulated sugar, and strawberry puree, whisking until well blended.
03 - Incorporate eggs and vanilla extract into the mixture, whisking until the batter is smooth.
04 - In a separate bowl, whisk together all-purpose flour, baking powder, and salt.
05 - Gently fold the dry ingredients into the wet mixture until just combined, avoiding over-mixing.
06 - Pour the batter into the prepared pan and smooth the surface with a spatula.
07 - Bake for 22 to 25 minutes, or until the edges are set and a toothpick inserted into the center emerges with a few moist crumbs.
08 - Allow to cool completely in the pan before glazing.
09 - Whisk together powdered sugar, strawberry puree, and lemon juice (if using) until the glaze is smooth and pourable.
10 - Spread glaze evenly over the cooled brownies. Allow to set for 15 minutes, then cut into squares and serve.