Preheat oven to 350°F (175°C) and grease the baking dish with butter
Cut keto bread into cubes and spread half evenly in the dish
In a bowl, mix cream cheese with a small portion of sweetener until smooth
Spread the cream cheese mixture over the bread layer
Add a layer of mixed berries evenly on top
Cover with remaining bread cubes to create layers
In another bowl, whisk eggs, heavy cream, almond milk, remaining sweetener, vanilla extract, and cinnamon
Pour the custard mixture evenly over the layered bread
Let it sit for 10–15 minutes to absorb the liquid
Bake for 35–40 minutes until the top is golden and set
Remove from oven and let cool slightly before serving