Preheat the oven to 325ºF (165ºC). Line an 8-inch square baking pan* with parchment paper.
In a medium microwaveable bowl, heat the white chocolate and butter in the microwave for 20 second intervals until melted. Alternately, melt the white chocolate and butter on the stove in a large heat safe bowl set over a pan of barely simmering water. Stir gently until smooth.
In a large bowl, whisk together the sugar, eggs, egg yolk, lemon juice, zest and salt until smooth and well combined. Stir in the melted white chocolate mixture with a rubber spatula. Add the flour and stir just until combined.
Gently fold in the raspberries.
Transfer the batter to the prepared baking pan. Bake until the top is set, the edges are light golden brown and a toothpick inserted into the center comes out with a few moist crumbs on it, about 23-28 minutes.
Let cool completely. Top with Raspberry Lemonade Icing.
Raspberry Lemonade Icing
In a small bowl, smash the raspberries with a fork.
Add the powdered sugar, melted butter and 1 tablespoon of lemon juice. Whisk until smooth, adding more lemon juice as needed.
Spread the icing over cooled brownies.
Cut into 2-inch squares and serve with additional raspberries, if desired.