Combine the first 4 ingredients in a medium bowl, stirring with a whisk.
Remove casings from sausage. Cook sausage in a large nonstick skillet over medium-high heat until lightly browned; stir to crumble. Add onion; cook 3 minutes or until onion is tender. Stir in chard; cover and cook 3 minutes or until chard wilts, stirring occasionally. Uncover and cook 1 minute or until liquid evaporates. Stir in egg mixture; cook 3 minutes or until eggs are set, stirring frequently. Serve with toast.