To start, cut the bread you'll be using into thick ½" to 1" slices. Butter your 9x13" casserole dish very liberally. Place your bread slices in the arrangement you'd like until the bread reaches the top rim of the dish. Bake the bread off for 10 minutes at 250°F to dry out the bread a bit.
While the bread is in the oven, in a medium-sized bowl, mix the softened cream cheese, vanilla extract, lemon juice, zest, salt until well combined. Set to the side.
In a large bowl, whisk the custard ingredients together until well combined. Set to the side.
Once the casserole is out of the oven, place the berries you're using over the top of the casserole and try to push many down so they reach the bottom and middle of the dish. Make sure the berries are spread to a variety of places in the dish.
Now, use a spoon to dollop the cream cheese mixture into the casserole. Again, ensure you spread to a variety of places in the dish. Make sure to get the corners, middle, top, etc.
In a medium bowl, use your clean hands to combine the streusel topping ingredients until it all clumps together and resembles the texture of wet sand. Sprinkle this topping over the top of the casserole as evenly as possible.
Bake the casserole at 350°F for 40 minutes, half the time covered with foil and the remaining half uncovered.
Wait for about ten minutes for the casserole to "settle" so you can cut into it without it totally falling apart. Serve warm and enjoy!