Cinnamon Blueberry Crumble Bars

These are absolutely heavenly!

1 box plain yellow cake mix
1 cup (2 sticks) butter, melted
1 cup old-fashioned oatmeal
1/2 cup packed light brown sugar
2 large eggs
1 tsp ground cinnamon
2 cups fresh blueberries (I used the frozen ones that I picked back in June)
1/2 cup granulated sugar

1. Heat oven to 350.

2. Place the cake mix, butter, brown sugar, eggs, and cinnamon in a large mixing bowl. Blend with an electric mixer on low speed for 1- 1 1/2 minutes. The mixture will be thick. Reserve 1 1/2 cups for the topping. Transfer the remaining crust mixture into an ungreased 9x13 pan. Press down evenly so the crust reaches all the sides.

3. For the filling, mix the blueberries and the granulated sugar in a small bowl. Pour the blueberries evenly over the crust. Scatter clumps of the reserved topping over the berries. Place pan in oven.

4. Bake for 40-45 minutes, until light brown and bubbling. Cool before cutting into bars.