Cut the butter into small pieces and let it soften at room temperature until it's soft enough to leave a dent when pressed lightly. Allow the cream cheese to soften as well.

Place the softened butter and powdered sugar into a large mixing bowl. Using an electric mixer on low speed, blend until the sugar is fully incorporated.

Increase the speed to medium-high and whip until the butter becomes light and fluffy, doubling in volume.

Add the softened cream cheese and beat on medium-high speed until smooth and creamy.

Add eggs in two batches to the creamed mixture. Mix on low speed after each addition until fully incorporated. Avoid overmixing to prevent separation.

Combine the cake flour and baking powder, then sift the mixture into the wet ingredients.

Using a silicone spatula, gently fold the dry ingredients into the batter with a cutting and folding motion. Mix until smooth and glossy, ensuring no dry flour remains. Do not overmix.

Wash the blueberries, pat them dry with paper towels, and gently fold them into the batter.

Line the cake mold with parchment paper or foil for easy removal. Pour the batter into the mold and level the surface with a spatula.

Preheat the oven to 170°C (340°F). Place the cake mold in the middle rack and bake for about 45 minutes.

If the cake browns too quickly on top, cover it with foil to prevent burning. Use a toothpick to check doneness; it should come out clean when inserted into the center.

Remove the cake from the oven and let it cool on a wire rack for 5–10 minutes. Take the cake out of the mold and cool completely before slicing.