01 - Preheat oven to 350°F. Grease and line an 8x8-inch baking pan with parchment paper.
02 - In a large bowl, whisk together melted butter, granulated sugar, and strawberry puree until thoroughly blended.
03 - Add eggs and vanilla extract to the wet mixture. Whisk until the batter is smooth.
04 - In a separate bowl, whisk together all-purpose flour, baking powder, and salt.
05 - Fold dry ingredients into the wet mixture until just combined. Avoid overmixing.
06 - Pour batter into the prepared pan. Smooth the surface with a spatula. Bake for 22 to 25 minutes, or until the edges are set and a toothpick inserted in the center yields a few moist crumbs.
07 - Allow brownies to cool entirely in the pan before glazing.
08 - In a small bowl, whisk together powdered sugar, 2 to 3 tablespoons strawberry puree, and lemon juice if using, until the glaze is smooth and pourable.
09 - Spread the glaze over cooled brownies. Let the glaze set for 15 minutes. Cut into squares and serve.