Preheat your convection air oven to 325 degrees Fahrenheit. If you don’t have a convection option, set it to 350 degrees and remember to rotate the pan halfway through the baking time to ensure even baking.
Prepare your loaf pan by buttering and flouring it. I recommend using a pan that measures 8.5 x 4.5 x 3 inches. After buttering and flouring, line it with parchment paper to make removal easier.
In a mixing bowl, combine cake flour with baking powder and salt. Sift this mixture three times, or alternatively stir it with a wire whisk until well combined, and set aside.
In a small saucepan over medium heat, add 2 tablespoons of butter to brown. Keep an eye on it until it turns a nice amber color, then remove it from the heat and set aside to cool.
In another bowl, whisk together your eggs and vanilla extract, and set this aside too. This mix will add depth to your batter.
In a large mixing bowl, cream the unsalted butter on medium speed. Gradually add the sugar while mixing until the mixture is smooth and creamy.
Now, add the heavy cream and mascarpone cheese to the mixture, beating on medium speed just until combined. Then, lower the mixer speed and gradually incorporate the dry ingredients and the egg mixture alternately until they are just combined.
Take about one tablespoon of the flour and toss the white chocolate chips in it to coat evenly. This helps prevent them from sinking in the batter. Also, toss the diced strawberries in a handful of flour.
Gently stir the coated chocolate chips into the batter, followed by the strawberries. Pour the batter into the prepared pan, smoothing the top. Tap the pan gently on the working surface to release any air bubbles.
Take a butter knife and draw a line down the center of the batter. Carefully pour the browned butter into this line; this will add a lovely flavor during baking.
Bake your cake until the top is golden brown and a toothpick inserted in the center comes out clean, which should take about 60 to 70 minutes.
Once baked, let the cake cool in the pan for 15 minutes. Then, carefully remove it from the pan and transfer it to a wire rack to cool completely.
For the frosting, cream together the softened butter and cream cheese until smooth, then slowly add in the powdered sugar on low speed. Mix in the vanilla extract and spread the frosting on top of the cooled cake. Place the cake in the fridge to set the frosting.
In a saucepan over low heat, melt 1/2 cup of white chocolate chips with 1 tablespoon of vegetable oil, stirring until smooth. If it's too thin, let it cool for a few minutes to thicken slightly before drizzling over the cake.
Finally, scatter the diced strawberries on top of the frosting, and drizzle with the melted white chocolate. To store, keep the cake in the fridge.
