Lightly spray a 9x13inch cake pan with cooking spray, set aside.
For the Cake:
Place the butter and 1 1/2 cups brown sugar in the bowl of your mixer, fitted with the paddle attachment, and mix until creamy and fluffy. Add the egg and vanilla and mix to combine. Combine the flour and baking soda in a bowl, then alternate adding the buttermilk and 1/2 cup at a time of the flour mixture until combined. Batter will be thick.
Fold in the raspberries very gently, as to not squish them too much. Pour batter into pan and spread into even layer.
For the Cheesecake Swirl:
Place the cream cheese, egg yolk, sugar and vanilla in the bowl of your stand mixer, fitted with the paddle attachment and beat until smooth and creamy. Place tablespoons of the mixture on top of the cake all over, then use the dull edge of a butter knife and run it up and down the cake, then back and forth to create a swirled effect.
For the Topping:
Combine the brown sugar, flour, cinnamon and melted butter in a bowl and stir to combine. Sprinkle brown sugar mixture over the top of the cake evenly.
Bake for 40 to 50 minutes or until toothpick inserted in center comes out clean. Let cool completely then enjoy!
Feel free to switch up the type of berries used in this recipe!