Fill a pot with 4 cups of cold water. Add the grits and stir. Cook over medium heat, stirring occasionally, until thick and creamy, about 20 minutes.
Let grits cool for about 15 minutes, until they just start to harden.
Meanwhile, preheat oven to 400 degrees (if using puff pastry)
Scoop a heaping spoonful of grits into a muffin tin or ramekin, allowing it to fill the dish about 3/4 of the way.
Add 1/4 of the sausage, cheese, kale, and onion to the center of the grits, and press into the middle.
Cover the filling with more grits, and press into the dish.
If using puff pastry, cut the sheet into quarters.
Overturn each ramekin onto one quarter of the puff pastry sheet, and then wrap the sheet around the grits cake. Replace the pastry-wrapped cakes to the ramekins or muffin tins (it’s probably easier to use a ramekin if you’re using the pastry dough).
Bake at 400 degrees until golden brown, about 20 minutes.
