Step 1

Preheat oven to 350 degrees.

Step 2

Lightly grease the bottom of a 9x13'' pan.

Step 3

Add blackberries and lemon juice to bottom of the pan, stir.

Step 4

Sprinkle with brown sugar.

Step 5

Then, top with yellow cake mix. Smooth with a spoon until even.

Step 6

Cut butter into tablespoon size, 12 total pieces. Lay the butter pieces evenly over the top of the cake mix.

Step 7

Bake until the top is bubbly and golden brown, about 35 minutes.

Step 8

Serve warm or room temperature with vanilla ice cream.