Preheat your oven to 400°F and grab a large baking sheet or 9x13 inch baking dish. Cut baby potatoes into quarters or halves—keep them bite-sized and uniform. Slice your smoked sausage into rounds about ½-inch thick. Melt your butter and mix it with olive oil in a small bowl. Have your ranch seasoning ready to go. If you're using fresh garlic, mince it now.

Dump the cut potatoes into a large mixing bowl. Add the sliced sausage right on top. Pour the melted butter and oil mixture over everything. Sprinkle the entire packet of ranch seasoning mix over the top. Add minced garlic if you're using it. Toss everything together until every piece is coated. Season with a bit of salt and pepper but go easy—the ranch and sausage are already salty. Make sure the ranch coating is visible on the potatoes.

Spread everything in a single layer on your baking sheet. Don't pile them up or they'll steam instead of roast. Make sure there's space between pieces for air circulation. Bake at 400°F for 30-35 minutes, stirring halfway through. The potatoes should be fork-tender and have golden crispy edges. The sausage should have some caramelized spots. If things aren't crispy enough, crank it to 425°F for the last 5 minutes.

Pull the pan out when the potatoes are done. Sprinkle shredded cheddar cheese evenly over everything. Pop it back in the oven for 5-7 minutes until the cheese melts. Don't leave it too long or the cheese will separate and get greasy. Let it rest for 5 minutes before serving. Garnish with chopped green onions if you're feeling fancy. Serve straight from the pan.