Preheat the oven to 160β/300β
Heat the olive oil in a large Dutch oven/cast iron casserole pot and brown the beef chunks seasoned with salt and pepper over medium heat until golden. Do this in batches to avoid overcrowding.
Move the browned beef to one side of the pot and lower the heat, then add chopped onions and thyme, cook over low heat for 8-10 minutes until tender. Then add minced garlic and cook briefly for 30 seconds.
Add the flour and stir the beef, so itβs coated, then add the water or beef stock if using and scrape the bottom of the pot with a spatula to release the brown bits at the bottom. Add the Guinness, one or two bay leaves, turn the heat up and bring to a boil. Then cover with a lid and put in the preheated oven for 1 hour.
After one hour take out of the oven and add carrots, butternut squash, cut into large chunks and potatoes to the pot, stir and add 250ml/1 cup of water, cover with a lid and continue cooking the stew in the oven for 1 more hour.
Prepare the dumplings by mixing the buttermilk, egg, oil, flour, baking soda, garlic powder, onion powder, and salt with a wire whisk in a medium bowl. The batter will be sticky and have the consistency of a waffle batter.
Take the stew out of the oven and scoop the batter directly on top of the stew. You can use two spoons for easy release or an ice cream scoop. Cover with a lid and put in the oven for 10 minutes, then take the lid off and cook for 10 minutes longer until the dumplings are golden.