1. Preheat oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
2. In a medium bowl, whisk together flour, sugar, baking powder, baking soda, and salt.
3. In a separate large bowl, cream together softened butter and sugar until light and fluffy.
4. Beat in eggs, one at a time, mixing well after each addition. Add vanilla extract.
5. Mix in sour cream and milk until well combined.
6. Gradually add dry ingredients to the wet ingredients, mixing until smooth.
7. Fold in fresh strawberry puree until evenly distributed.
8. Divide batter evenly between the prepared cake pans.
9. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.
10. Remove cakes from oven and let cool in pans for 10 minutes. Then, transfer to wire racks to cool completely.

For the vanilla bean frosting:

1. In a large bowl, beat softened butter until creamy.
2. Gradually add powdered sugar, one cup at a time, beating well after each addition.
3. Add milk or cream, one tablespoon at a time, until desired consistency is reached.
4. Mix in scraped vanilla bean seeds or vanilla bean paste until evenly distributed.

To assemble:

1. Place one cake layer on a serving plate. Spread a layer of vanilla bean frosting over the top.
2. Carefully place the second cake layer on top. Frost the top and sides of the cake with the remaining frosting.
3. Optional: Garnish with fresh strawberries or strawberry slices.