Preheat a cast-iron griddle over low heat; preheat the oven to 300 degrees F.
Combine the cream cheese, jam and slivered almonds in a small bowl and beat with an electric mixer.
Slice the challah into 2-inch-thick slices. With a pairing knife, make a 1/2-inch horizontal slit in the bottom crust of each slice to form a pocket.
Using a butter knife, fill each slice with some of the cream cheese mixture. Set aside.
Whisk together the eggs, almond extract, brown sugar and milk in a large baking dish. Dip the stuffed challah slices into the egg mixture, turning to fully coat each slice.
Increase the temperature on the preheated griddle to medium heat; add the butter, let it melt, and then place the stuffed and dipped challah onto the griddle. Cook until golden brown, about 4 minutes per side. Transfer to a baking sheet fitted with a baking rack, and hold in the oven to keep warm. Serve with slivered almonds and maple syrup.