The night before baking, cut the sourdough into 1-inch cubes. You want big chunks, not tiny pieces. Set aside.
STEP 1: CUBE THE BREAD
STEP 2: MAKE THE CINNAMON SUGAR FILLING
In a small bowl, mix softened butter with brown sugar, cinnamon, and salt until it forms a thick cinnamon-sugar butter.
STEP 3: LAYER THE BREAD AND FILLING
Grease a 9x13-inch baking dish. Add half the bread cubes. Spoon most of the cinnamon-sugar mixture over the bread. Add the remaining bread and mixture.
STEP 4: WHISK THE CUSTARD (EGG MIXTURE)
In a large bowl, whisk eggs, heavy cream, milk, granulated sugar, vanilla, and salt until smooth.
STEP 5: POUR, PRESS, AND CHILL OVERNIGHT
Pour the custard evenly over the bread. Gently press the bread down so the top layer gets soaked. Cover tightlY and refrigerate for 8 to 10 hours.
STEP 6: ADD STREUSEL (OPTIONAL)
Right before baking, make the streusel. Mix brown sugar, flour, butter, cinnamon, and pecans (if using) until crumbly. Sprinkle evenly over the casserole.
STEP 7: BAKE
Preheat oven to 350°F. Bake for about 40 minutes, until golden, bubbly, and set in the center.
STEP 8: REST AND SERVE
Let it rest 10 minutes before serving. This helps the custard finish setting so slices hold together.
Serve warm.
PRO TIPS
- Press the bread down after pouring the custard to ensure everything soaks
- Use cold butter for the streusel for ideal texutre
- Add blueberries between layers for extra sweetness
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