Preheat the oven to 350°F
Line the bottoms of two 9-inch cake pans with parchment paper rounds and grease the sides.
Beat butter and sugar together until fluffy.
Add sour cream and strawberry extract.
Add egg whites in 2 batches.
Combine the flour, baking powder and salt in a bowl.
Combine the milk and puree in bowl.
Add half of the flour mix to the batter.
Add the milk mixture to the batter and combine.
Add rest of flour mix.
Add coloring.
Divide batter between the 2 pans and bake 25-30 mins.
Cool a few mins, then remove to a rack and cool to room temp.