Preheat oven to 350°F. Prepare cake rounds with non-stick cooking spray.

Combine dry ingredients (flour, baking soda, baking powder, salt) in medium bowl; set aside.

In large mixing bowl cream butter, add sugar until smooth. Add eggs one at a time, beat thoroughly after each addition then beat until fluffy.

Add approximately half the blackberry puree; mix well. Add vanilla extract, mix. If adding food coloring, do that now.

Alternately add flour, yogurt, and puree. Mix well, until just combined.

Batter is thick. Divide evenly among 8" rounds.

Bake cakes approx. 32-37 minutes.

Cool cake rounds for 10 minutes before removing cake to cooling rack.