Transfer fromage blanc to a medium bowl and set aside at room temperature. Heat oil in a large skillet over medium heat.

Add kielbasa and cook, flipping once, until browned on both sides, about 10 minutes; transfer to a plate.

Return the skillet to the heat, add onion and cook, stirring often, until golden, 5 to 7 minutes.

Add greens, salt and 1/4 cup water; cover and cook, stirring once or twice, until very tender, about 10 minutes more.

Using tongs, transfer greens to a large bowl, leaving residual liquid in the skillet. (You'll need at least 1/4 cup, so add more water, if needed.)

Whisk to scrape up any browned bits and to make sure liquid is very hot, and then slowly whisk hot liquid into fromage blanc to make a sauce.

Gently stir sauce into collard greens, transfer to plates top with kielbasa and serve.