Heat half the butter on a medium high heat in a large frying pan. Remove sausage casings and crumble the sausage meat into the pan.
Cook, stirring and breaking up any large chunks of sausage meat for a few minutes or until sausage meat is starting to brown.
Add the remaining butter, mushrooms and thyme. Continue to cook, stirring every now and then until the mushrooms are tender and brown and the sausage meat is all cooked through.
Taste and season. Serve on a bed of the baby spinach OR add the spinach to the pan and cook for another few minutes or until just starting to wilt.