McDonald's beloved Egg McMuffin has stayed pretty consistent in its recipe since its debut 50 years ago — but one ingredient swap changed the breakfast sandwich for the better.

McDonald’s franchisee Herb Peterson began development of the Egg McMuffin back in 1971. During early testing, a couple of sweet components were offered on the side.

For one day only, McDonald's will celebrate National Egg McMuffin Day on Sunday, March 2 with an Egg McMuffin or Sausage McMuffin with Egg breakfast sandwich for just $1, available exclusively ...

Purchase an Egg McMuffin or Sausage McMuffin with Egg for $1 through the McDonald's app on Sunday.

McDonald's will sell its McMuffin breakfast sandwiches for $1 on Sunday to celebrate the 50th anniversary of its nationwide rollout of the Egg McMuffin.

McDonald's is offering a special deal on one of its most iconic breakfast items, the Egg McMuffin, to mark its 50th anniversary.

On Sunday, McDonald's is selling $1 Egg McMuffins on its app. The promotion comes as the Egg McMuffin celebrates 50 years on the market and as egg prices soar.

McDonald's announced a new $1 breakfast sandwich on National Egg McMuffin Day, plus more promos and the launch of bagel sandwiches to celebrate 50 years of the menu.

The Egg McMuffin, first introduced in 1975, is turning 50 this year. To honor five decades of yellow wrapper goodness, McDonald's is offering promotional deals throughout March.

It's the 50th anniversary of the egg McMuffin, and fans get the presents while McDonald's celebrates this weekend. See the deals.

McDonald's is offering breakfast lovers the chance to get an Egg McMuffin or Sausage McMuffin with Egg on March 2 to mark 50 years since the launch of the famous sandwich.