Place the flour, sugar, 1/2 cup plus 2 tablespoons water, milk, butter, eggs and salt in a blender and process until smooth, about 5 seconds. Turn off the motor. With a rubber spatula, scrape down the sides of the blender, and blend the batter for 20 seconds longer. Transfer the batter to a bowl and let it stand, covered, for 1 hour. The batter may be made 1 day in advance and kept covered and chilled.
Meanwhile, blend the cajeta, whipping cream and cream cheese in a clean blender until smooth. Set aside.
Heat a crepe pan or nonstick skillet measuring 6 to 7 inches across the bottom over moderate heat until it is hot. Brush the pan lightly with butter and heat until the pan is hot but not smoking. Stir the batter and pour 1/4 cup of the batter into the pan. Tilt and rotate the pan quickly to cover the bottom with a layer of batter. Loosen the edge of the crepe with a spatula, and cook the crepe until the top appears almost dry, about 1 minute. Flip the crepe, cook the other side lightly and transfer the crepe to a plate. Make crepes with all the remaining batter, brushing the pan lightly with butter as necessary.
To assemble: On a 10-inch cake stand, or in a 9-inch glass pie dish, pour 1/4 cup cajeta cream into the center. Top with one crepe, more cajeta cream, sliced bananas and pecans. Repeat with remaining crepes, cream, bananas and pecans, finishing the last layer with bananas and pecans. Refrigerate until set, about 45 minutes. Serve cold.