I think this is taster if you used spicy sausages rather than just plain ones. You can use canned mushrooms instead of fresh ones. Finely chop all the ingredients shown in the picture.
Put the chopped ingredients into a pot and stir fry thoroughly. You don't need oil as oil will render from the sausages. If there's excess fat, absorb with paper towels.
Add the butter and melt completely.
Add the flour a little at a time. You want to cook so that the bottom of the pot browns but doesn't burn.
Add the milk and mix thoroughly. It will burn if it boils, so turn the heat to medium.
Add the soup stock cube and mix to dissolve. You can also use consomme powder. Season with salt and pepper (how much you need depends on the kind of sausages you're using).
If using for biscuits (scones) or toast, this is enough for 4 servings. For pasta, it's enough for 2. You can also use it in gratin.
A picture of it poured top of biscuits made with Recipe ID: 735409. Adding a bit of parsley mades it nice and colorful.
Story Behind this Recipe
I wanted to make some gravy sauce for meat, and while I was looking on the internet for ideas, I found sausage gravy. This is my original version, that I came up with after a bit of experimentation.
Be sure not to take your eyes off the pan, keeping watch so that it doesn't burn. Other than that, it's easy. Add the milk bit by bit until it reaches your desired consistency. You can also add in your favorite vegetables, or make it just using sausage, butter, flour, and milk.