Preheat the oven to 325ºF (165ºC). Line an 8-inch square baking pan* with parchment paper.
In a medium microwaveable bowl, melt the white chocolate and butter in the microwave for 20 second bursts, stirring after each one. Alternately, melt the white chocolate and butter on the stovetop in a 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. Add the flour and mix just until combined. Gently stir 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 the brownies cool in the pan.
Raspberry Lemonade Icing
In a medium-size 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 the cooled brownies.
Cut into 2-inch squares and serve with additional raspberries, if desired.