I cook in a slow cooker, but I tried to do it in the oven, it turns out no worse. If you cook in the oven, then put the grits in the cauldron, add the hearts, water and salt. Cover and place in the oven, preheated to 180 degrees, for 40-50 minutes. Be guided by your own.
I fry immediately in the bowl of a slow cooker, so I add all the same ingredients, set the “cereals” mode (“buckwheat porridge”, “stewing”), close the lid and forget about buckwheat for 40 minutes.