This is a favorite recipe I've modified from the very, very good book Slow Cooker Revolution (affiliate link). I've adjusted the seasoning and sweetness to my taste, so feel free to do the same for yourself. I start the oats late in the evening, before bed, or prepare the dry ingredients ahead in batches and freeze.
I started by melting 2 tablespoons butter in a 12-inch skillet; I used my Lodge cast iron skillet. When I'm preparing multiple batches, I use a 7-quart Dutch oven.
I measured 2 cups steel-cut oats. They are cheapest in the bulk section if a health food store, but you can even buy them in Walmart now. The fanciest ones are imported from Ireland. "Old-Fashioned" rolled oats are steamed and rolled flat; steel cut oats are sliced (by steel blades) rather than being flattened. They have more flavor and fiber than the rolled oats, but take longer to cook. Un-violated oats are called oat groats, and the intact grain is very slow to cook.
I toast the oats in the butter until medium brown. Toasting is optional, but I never skip it; If I'm going to make "real" oatmeal, I might as well go all the way. I tried very hard to capture the color above, but I'm not the best photographer. You're going for slightly darker color on average, with none if the oats reaching the dark-brown burned state, which would flavor the whole batch.
I add the toasted oats to my large slow cooker, along with 1 teaspoon salt, 1 teaspoon cinnamon, and 3/4 cup light brown sugar. These amounts are all adjustable to your taste. I've added raisins, but the long cooking time makes them a little prune-y.
Next I add 8 cups water, or 1/2 gallon. Conveniently, I have a 1/2 gallon water pitcher from the Dollar Store.
Things do not look delicious at this point :-) I went to bed.
The ideal cooking time is 4-6 hours on low. This works for us because my husband gets up earlier in the morning than I do. It's not really a problem if the oats go a bit longer though.
In the morning, the oatmeal looks like this.
It's less exciting but more homogeneous after being stirred.
My husband and I eat a filling portion with milk, then he (wonderful man) refrigerates the rest in 1-serving portions.
On a personal note, I will be posting less frequently for a while. My mother is very ill, and I'm spending a lot of time with her.
Irish Oatmeal in a Slow Cooker
Adapted from Slow Cooker Revolution from America's Test Kitchen
2 tbsp butter
2 cups steel-cut oats
1 tsp salt
1 tsp cinnamon
3/4 cup light brown sugar
8 cups water
Melt butter in 12-inch skillet over medium heat. Add oats and toast, stirring very often, until browned around the edges. Transfer to a 2-quart slow cooker.
Add salt, cinnamon, sugar, and water to slow cooker and cook on low 4-6 hours. Stir and serve with milk.
To prepare ahead, toast oats and transfer to a quart-sized freezer bag. Add salt, cinnamon, and light brown sugar. Freeze. The night before you want to eat the oatmeal, transfer the contents of the bag to the slow cooker, add water, and cook as above. You may easily prepare-ahead several batches of oatmeal in this manner, then freeze in individual bags for later cooking.