To make the sauce, combine milk, margarine, flour, salt, and pepper in a saucepan.
Cook and stir over medium-low heat until mixture thickens.
Remove from heat, add the cheese, and stir until cheese melts.
On 4 warmed plates, shape the cooked rice into 4 small nests.
Place a poached egg in middle of each nest.
Cover with sauce; top with olive slices.