Preheat your oven to 350°F (325°F if your oven runs hot or is convection/gas). Grease and line an 8x8-inch steel baking pan with parchment paper.
In a large bowl, combine the unsalted butter and white chocolate. Melt them together either in the microwave in 15-30 second increments (stirring in between) or over a double boiler until smooth.
Add the granulated sugar and 1/3 cup plus 2 tablespoons of strawberry puree to the melted butter and chocolate. Mix well with a whisk or a mixer.
Add the egg and egg yolks and beat on medium speed for about 3 minutes. Add a few drops of pink food coloring if you want a more vibrant pink.
Add the flour and salt. Mix on low until combined, then finish mixing with a spatula to avoid overmixing.
Pour the batter into the prepared pan and smooth the top with a spatula.
Bake for 35 minutes, or until the brownies are set around the edges and on top. A toothpick should come out clean when inserted into the center.
Let the brownies cool completely in the pan.