Tried for the first time using slightly more than 3 cups of frozen berries and a couple of substitutions. I didn't have a 1/2c sour cream so I used 1/4c regular (whole milk) yogurt and 1/4c low-fat Greek yogurt. I reduced the sugar in the egg mixture to 2/3c (instead of 1 c) and in the topping I also wanted to reduce the amount of sugar to make it a little more healthy so I used only 1/4 c sugar & 1/4 c all purpose flour with 1/4 c tapioca flour (which is sweet and crisps well) and 1/4c almond meal/flour. I baked for the full 55 min. It was yummy warm out of the oven and cold this morning.

This is one of the best pies I have made. I use my frozen blackberries that I pick from my yard and it is so good!