Cut bacon into small pieces, cook and drain (You could use precooked bacon to speed up the process).
In the bottom of a slow cooker, layer: half of the hash browns and half of the following: onions, bacon, green and red peppers and cheese. Repeat layers with the remaining ingredients ending with cheese.
In a medium sized bowl beat eggs and milk together. Pour egg mixture over the casserole and top with salt and pepper to taste.
Cook on Low for 6-8 hours (or high for 2 1/2 – 3 hours).