Start by washing your Yukon gold potatoes and cutting them into quarters. Try to keep the pieces roughly the same size so they cook evenly. If your potatoes are on the larger side, cut them a bit smaller so they turn tender in time.
Place the quartered potatoes into the bottom of your slow cooker first. Add the diced onion and drained green beans on top, spreading them out evenly. This layering helps everything cook at the right pace without the potatoes staying too firm.
Scatter the sliced smoked sausage over the vegetables so its flavor drips down through the layers as it cooks. Sprinkle the Italian seasoning packet, garlic powder, onion powder, smoked paprika, salt, and pepper evenly over everything.
Place the full stick of butter right on top of the mixture without cutting it up. As it melts down during cooking, it naturally distributes through the pot and creates that rich, glossy sauce everyone raves about.
Cover the crockpot with its lid and set it to cook on low for about 6 hours, or on high for 3 to 4 hours if you're short on time. You'll know it's ready when the potatoes are fork-tender and everything looks glossy and combined.
Once the cooking time is up, give everything a good stir so the melted butter and seasoning coat every piece of potato, sausage, and green bean. Serve it up hot right from the crockpot for the easiest cleanup possible.