Lightly spread about 1/4 teaspoon butter on one side of each tortilla; set aside. In a bowl, beat eggs and milk until combined.
Pour egg mixture into a hot, lightly greased skillet; cook and stir over medium heat until done. Remove scrambled eggs to a dish and keep warm.
Melt remaining butter in the skillet and add a tortilla, buttered-side down. Layer with 1/4 of the cheese, 1/2 of the eggs and 1/2 of the bacon. Top with 1/4 of the cheese and a tortilla, buttered-side up.
Cook one to 2 minutes on each side, until golden. Repeat with remaining ingredients. Cut each into 4 wedges and serve with salsa and sour cream, if desired.