In the top of each slice of bread, carefully cut a pocket in the bread, without cutting through the bottom or sides.
Using a butter knife, spread one tbsp of cream cheese and one tbsp of guava jam in the pocket of the bread slice.
To make the custard, in a shallow pan, beat the eggs, milk, rum, salt, and vanilla together.
Coat each side of each stuffed bread slice in the custard for 5 seconds.
Heat a large skillet over medium heat. Add a half tbsp of butter to the skillet once hot and add the slices of bread to the skillet. Allow to cook 2-3 minutes on each side, until golden. Cook in batches if needed to avoid overcrowding.
Preheat your oven to 375 degrees F (190 degrees C).
Place your cooked french toast slices on a baking sheet and bake in the preheated oven on the middle rack for 10 minutes. Remove and let cool 5 minutes before serving.
Top with a sprinkle of powdered sugar and enjoy!