Preheat the oven to 350°F (175°C). Grease and flour the cake pans.

In a mixing bowl, combine flour, sugar, baking powder, and salt.

Add softened butter, milk, eggs, and vanilla extract. Beat on medium speed until smooth.

Divide the batter into two bowls. Mix pureed strawberries into one bowl and blueberries into the other.

Pour the red batter into one prepared pan and the blue batter into the other. Bake for 25 minutes or until a toothpick comes out clean.

Let the cakes cool in the pans for 10 minutes, then transfer to wire racks to cool completely.

In a mixing bowl, beat the softened butter until creamy.

Gradually add powdered sugar, alternating with heavy cream, and beat until fluffy. Stir in vanilla extract.

Place the red cake layer on a cake stand. Spread a layer of frosting on top.

Add the blue cake layer on top and frost the top and sides of the cake.

Decorate with sliced strawberries and blueberries on top.