In medium mixing bowl, combine first 5 ingredients and whisk to combine. Add in brown sugar and dates and stir. Cut brioche bread into 1-inch cubes. Combine bread with egg and milk mixture and stir until bread is well coated.
Pour into an oven-safe casserole dish that will fit into your slow cooker.
Add ½ cup hot water to the slow cooker.
Put a trivet, aluminum foil shaped into a ring, or Mason jar lids onto the bottom of the slow cooker croc. Put the casserole dish on top of that.
Cover the slow cooker and cook on high for 2 hours. Serve pudding warm or cold.