Don't forget to toss your blueberries in cake mix or flour so they do not sink to the bottom of the pan while baking.
Pre-heat oven to 350 F.
Sift cake mix in medium sized mixing bowl and set aside.
Combine butter, vanilla, eggs and pineapple.
Take 1/2 cup cake mix and toss in blueberries to coat. Mix in remaining sifted cake mixture until combined.
Fold in blueberries (with any remaining cake mix) just until blended.
Pour cake mixture into prepared cake pan. Bake until took when inserted comes out clean, start checking at 25 minutes.
While cake is cooling, prepare frosting by blending butter, cream cheese and vanilla until smooth. Add powdered sugar one cup at a time, mixing well.
Frost cake and top with additional berries. Can be stored in an airtight container.