Start by making the strawberry coulis that will flavor the brownies. I have a whole detailed post about how to make strawberry coulis if you would like more in-depth information.
Put the strawberries and sugar in a high sided saucepan over medium heat.
Heat until the sugar dissolves and the strawberries start to break down, stirring occasionally, and let it continue boiling.
Keep boiling until the mixture thickens and starts to look slightly gelatinous. For more info on how to know your coulis is ready, read my strawberry coulis post.
Remove from the heat and let cool for 15 minutes, then transfer to a food processor or blender and blitz until smooth.
For extra smooth coulis, pass the strawberry puree through a fine mesh sieve (this step is optional).
Allow to cool to room temperature before using.
Make the Strawberry Brownies
Preheat the oven to 325°F / 170°C and line a 9" square baking pan with parchment paper.
Melt the butter and white chocolate in the microwave in 30-second increments, stirring in between each round, until completely melted and smooth. Set aside.
In a large bowl, whisk together the sugar, egg, and egg yolk for about 30 seconds or until the mixture is thick and pale - kind of like custard.
Add the vanilla to the egg/sugar mixture and stir in.
Pour in the melted white chocolate/butter mixture and stir until combined.
Sift in the flour, salt, and baking soda and mix until everything is combined and smooth.
Add 1 cup of the cooled strawberry coulis and mix together until combined.
If you want to, add a couple of drops of pink gel food coloring. This will give a nice vibrant color to your strawberry brownies. This is completely optional, the brownies will still taste amazing without it, they just won't be quite as bright in color.
Stir in the white chocolate chips until evenly distributed.
Pour brownie batter into the prepared cake pan and bake for 35 minutes, or until a skewer inserted comes out clean.
Let cool completely before frosting.
Make the Strawberry Ganache
Chop the white chocolate into small pieces and place them in a large bowl.
Heat the heavy cream in a saucepan on medium heat, just until tiny bubbles start to form on the surface.
Immediately pour the warm cream over the chopped chocolate and let it sit for 1 minute, then stir the chocolate and cream together until the chocolate is all melted and everything is silky smooth and combined.
Add ½ cup of the prepared strawberry coulis (or more, to taste) and mix until well combined. You can also add some food coloring to the ganache at this stage if you like, but the natural color is very pretty!
Let cool completely until thick enough to spread (you can put it in the fridge to speed up the process).
Spread over the cooled strawberry brownies and top with sprinkles, fresh strawberries, or crushed, dried strawberries.
Slice the brownies into 9 or 16 equal squares and enjoy!
Notes
Make the strawberry coulis in advance so it has time to cool before making the strawberry brownies. I have a full blog post all about how to make strawberry coulis if you would like more in-depth instructions. For best results, always weigh your ingredients with a scale rather than with cup measures - scales are far more accurate and will give you better end results in your baking. All my recipes have measurements in both cups and grams listed in the recipe card.