Preheat the oven to 350º F. Prepare three 9-inch round cake pans with nonstick baking spray or prepare with butter and flour. Remove any excess flour.
Blend the strawberries in a blender on medium speed until pureed, about 3 minutes. This should result in 3/4 cup strawberry puree. Set aside.
Cream together the butter and shortening with an electric mixer until light and fluffy. Slowly add the sugar, one cup at a time, making sure to fully incorporate each cup before adding another. Add eggs one at a time, making sure to fully incorporate each egg before adding another.
Sift together the flour, baking powder, and salt in a medium bowl. Pour milks, vanilla, and the strawberry puree into a measuring cup and whisk together with a fork. Alternately add the flour mixture and the milk mixture to the butter and shortening, beginning and ending with the dry ingredients.
Gently stir all ingredients until well combined. Stop the mixer and scrape down the sides and bottom of the bowl, making sure to have all ingredients well mixed.
Evenly distribute the batter between the cake pans and place the pans into the preheated oven. Bake for 30 to 40 minutes, or until the cake releases from the edges of the pan and springs back to a light touch. Remove the pans from the oven and allow to cool in the cake pans for about 10 minutes. Turn the cakes out onto wire racks and let them cool completely.
Frost cake with strawberry buttercream frosting.
If a more pronounced strawberry flavor is desired, add 1 teaspoon strawberry extract to the cake batter as you are adding the vanilla extract. If you would like a more pronounced pink color to your cake, add 1 - 2 drops of natural pink or red food coloring to the batter.