To a large cast iron skillet over medium-high heat, add the olive oil. When the oil begins to shimmer, carefully add the sausages and slowly pour on the stout. Reduce the heat slightly and cover with lid. Crack the lid just to allow enough steam to escape. Cook the sausages and stout covered for about 10 minutes, turning halfway through.

After the sausages have cooked for 10 minutes, remove lid and allow the liquid to reduce a bit and coat the sausages. When the liquid is almost gone, lower heat to low and continue cooking with the lid on, rotating occasionally, until evenly browned and cooked through, about another 10 minutes. Sausages will begin to glaze and become dark and shiny.

In a separate deep skillet, heat butter over medium high heat. Add the sliced yellow onions and reduce the heat to medium low. Cook until lightly golden and very fragrant, about 20 minutes. Add the fresh thyme leaves and stir for a minute until the thyme becomes aromatic.

Sprinkle flour over top the onion mixture and allow to cook 2 to 3 minutes more. Slowly pour in stout and scrape bottom of pan to deglaze and loosen brown bits. Add Worcestershire sauce and beef broth, stir, and allow to simmer until no longer foamy, about 15 minutes. Stout onion gravy will thicken upon standing.

Fill a large pot with water and 1 tablespoon of Kosher salt. Add prepared potatoes and bring to a boil. Cook potatoes until they become somewhat soft.

While potatoes cook, melt butter in a saucepan along with buttermilk, salt and pepper. You only need to heat the buttermilk enough to warm it.

When the potatoes are done, drain well and add back to the pot. Place the pot back atop the still hot burner and shake the pan to encourage any heat that remains on the burner to further dry the potatoes out.

Combine the buttermilk with the potatoes and use a handheld potato masher to mash and cream the potatoes.

Assemble a heap of potatoes in several wide shallow bowls. Ladle generously with the Guinness stout onion gravy and top with a couple or three bangers. Enjoy with a pint and wedges of warm Irish soda bread.