FOR THE SAUCE: In a saucepan, saute green pepper and onion in butter or margarine until tender. Stir in flour, horseradish mustard, spices and milk. Stir until mixture is thick and bubbly. Cover; keep sauce warm.
In a lightly-greased skillet, boil 2-inches of water; reduce heat to simmer. Break 1 of the eggs into cup; carefully slide egg into simmering water. Repeat with remaining eggs, keeping them separate in the skillet. Simmer, uncovered, over low heat for 3 to 5 minutes. Remove eggs with slotted spoon and drain.
Top each muffin half with a slice of Swiss cheese and poached egg; spoon sauce over each egg. Sprinkle with paprika.