In a large skillet (see note), heat 1 Tbsp olive oil over medium-high heat. Add sausage and saute until golden brown, 5 to 7 minutes.
Add Swiss chard to chicken sausage and cook, stirring constantly, until chard is wilted, 3 to 4 minutes more. Transfer sausage and Swiss chard to a plate or bowl and return skillet to heat.
Reduce heat under skillet to low-medium. Add remaining 2 Tbsp olive oil and butter. Stir gently until butter melts.
Add potatoes in a single layer and cover with a lid.
Cook potatoes, covered, without stirring them, for 10 minutes. (Resist the urge to lift the lid and check them - keeping the lid closed helps them to steam and cook through until tender.)
Remove the lid and use a spatula to gently flip the potatoes. Scatter onions over the potatoes. Cover again and continue to cook for 10 minutes more.
Remove lid and stir in salt, paprika, and garlic powder. Continue cooking potatoes until they can be easily pierced with a fork (depending on the size, they may already be done or may need up to 5 minutes more).
Gently fold in sausage and Swiss chard.
Serve warm. (Great with a fried or poached egg on top!)