Preheat your oven to 350°F (175°C). Grease and flour three 9-inch round cake pans.

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

In a large mixing 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 wet mixture, alternating with the milk. Begin and end with the flour mixture, mixing until just combined.

Divide the batter evenly into three bowls. In one bowl, add red gel food coloring until you reach your desired shade. In the second bowl, add blue gel food coloring. Leave the third bowl plain.

Pour the red batter into one prepared cake pan, the blue batter into another, and the plain batter into the last pan.

Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted in the center comes out clean. Let the cakes cool in the pans for 10 minutes before transferring to wire racks to cool completely.

While the cakes are cooling, whip the heavy cream with the powdered sugar and vanilla extract until stiff peaks form.

Once the cakes are completely cool, place the red layer on a serving plate. Spread a layer of whipped cream on top, then add the blue layer. Repeat with more whipped cream, then top with the plain layer.

Frost the top and sides of the cake with the remaining whipped cream. Decorate with fresh strawberries and blueberries on top for a festive look.