Place 2-3 in. of water in a large skillet with high sides. Bring to a boil; reduce heat and simmer gently. Break cold eggs, one at a time, into a custard cup or saucer; holding the cup close to the surface of the water, slip each egg into water. Cook, uncovered, until whites are completely set and yolks begin to thicken but are not hard, about 4 minutes.
Meanwhile, in a small saucepan, combine the flour, salt, mustard and cayenne. Gradually stir in milk and evaporated milk until smooth. Bring to a boil; cook and stir for 1-2 minutes or until thickened. Remove from the heat.
Stir a small amount of sauce into egg yolk; return all to the pan, stirring constantly. Bring to a gentle boil; cook and stir for 2 minutes. Remove from the heat; stir in butter-flavored sprinkles and lemon juice.
With a slotted spoon, lift each egg out of the water. Top each muffin half with a slice of bacon, an egg and 2 tablespoons sauce. Serve immediately.
This recipe was tested with Molly McButter. Look for it in the spice aisle.