Preheat the oven to 350°F (175°C). Grease and flour a 10-inch bundt pan.

In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.

In a large bowl, cream the softened butter and granulated sugar together until light and fluffy, about 3-4 minutes.

Add the eggs, one at a time, mixing well after each addition. Stir in the vanilla extract.

Gradually add the dry ingredients to the butter mixture, alternating with the whole milk, starting and ending with the flour mixture. Mix until just combined.

Divide the batter into three equal portions. In one bowl, mix in the pureed strawberries. In the second bowl, mix in the pureed blueberries. Leave the third portion plain.

Spoon the batters into the prepared bundt pan, alternating colors to create a marbled effect. Use a knife to swirl the batters together gently.

Bake for 50-60 minutes, or until a toothpick inserted into the center comes out clean. Allow the cake to cool in the pan for 15 minutes before inverting onto a wire rack to cool completely.

For the glaze, whisk together the powdered sugar and milk until smooth. Drizzle over the cooled cake.