Start by preparing the raspberry filling. Thaw the frozen raspberries, making sure to reserve 3 tablespoons of the juice. Using a fine sieve, strain half of the raspberries to eliminate seeds, which will give the filling a smoother texture. Combine the sieved berries with the remaining whole raspberries and their juice.

In a small saucepan, mix the reserved 3 tablespoons of raspberry juice with the lemon juice, cornstarch, and sugar. Heat this mixture over medium heat, stirring continuously until it reaches a boil. This activates the cornstarch, thickening the filling.

Once boiling, add the combined berries to the saucepan. Let everything simmer for about a minute while stirring. The berries should soften slightly in this time. After simmering, take the saucepan off the heat, transfer the filling to a bowl, and let it cool in the refrigerator for at least two to three hours, or overnight if you prefer.

While the raspberry filling is cooling, move on to making the brownie batter. In a large mixing bowl, combine the melted butter with both the brown sugar and granulated sugar. Mix until well blended, creating a smooth base for your brownies.

Incorporate the vegetable oil, powdered sugar, and cocoa powder into the butter and sugar mixture, stirring until it achieves a homogenous consistency.

Add the eggs, vanilla extract, and salt to the bowl, stirring well until everything is well combined.

Gradually mix in the flour, taking care to combine just until no streaks remain. The batter should be thick but smooth.

In a clean mixing bowl, beat the cream cheese until it’s smooth. Add the granulated sugar and vanilla extract, mixing until fully combined and creamy.

Before baking, preheat your oven to 350°F. Prepare a 10×10 pan by lining it with parchment paper.

Pour the brownie batter into the prepared pan, spreading it evenly.

Using a spoon, dollop the cream cheese mixture over the brownie batter. Spread it gently to cover most of the brownie layer.

Spoon the cooled raspberry filling over the cream cheese layer. With a skewer or knife, gently swirl the raspberry filling and cream cheese together for a marbled effect.

Bake in the preheated oven for 40-45 minutes. Keep an eye on it; you want the edges to feel firm while the center has a slight wobble.

Once baked, allow the brownies to cool in the pan before cutting into them.