Prepare the Brownie Base:

1. Preheat the Oven: Preheat your oven to 350°F (175°C) and line an 8×8-inch baking pan with parchment paper, leaving an overhang for easy removal.
2. Make the Batter: In a microwave-safe bowl, melt the butter and stir in the sugar, eggs, and vanilla extract until smooth. Sift in the flour, cocoa powder, and salt, mixing until just combined.
3. Bake the Brownies: Pour the batter into the prepared pan and bake for 25-30 minutes or until a toothpick inserted into the center comes out with a few moist crumbs. Let the brownies cool completely.

Prepare the Strawberry Truffle Layer:

4. Make the Strawberry Puree: Blend fresh or thawed strawberries into a smooth puree.
5. Melt the White Chocolate: In a heatproof bowl, combine the white chocolate, heavy cream, and butter. Melt the mixture over a double boiler or in the microwave, stirring until smooth.
6. Combine the Flavors: Mix the strawberry puree into the melted white chocolate mixture until fully incorporated. Spread the truffle mixture evenly over the cooled brownie base. Chill in the refrigerator for at least 1 hour.

Prepare the Ganache Topping:

7. Heat the Cream: In a small saucepan, heat the heavy cream until it begins to simmer.
8. Melt the Chocolate: Pour the hot cream over the chopped semisweet chocolate in a heatproof bowl. Let it sit for 1 minute, then stir until smooth and glossy.
9. Top the Truffle Layer: Pour the ganache over the chilled truffle layer, spreading it evenly. Chill the brownies again for at least 1 hour or until the ganache is set.

Slice and Serve:

10. Slice the Brownies: Use a sharp knife to cut the brownies into squares. For clean cuts, wipe the knife with a damp cloth between slices.
11. Garnish and Serve: Garnish each brownie with fresh strawberry slices or sprinkles before serving, if desired.