Preheat your oven to 375 degrees F, and spray a large cast iron or other oven-safe skillet with a nonstick spray. Place the pan on the stovetop set over medium-high heat. Add the sausages and char on all sides until brown, about 2 minutes on each side. Remove the sausage from the pan and set aside.
In a medium bowl, whisk together the beer, mustards, mayo, cheese, olive oil, vinegar, garlic powder, onion powder, and salt and black pepper to taste. Add the potatoes and toss to coat. Pour the potatoes in the pan that you seared the sausage in.
Place the potatoes in the oven and roast for 25 minutes. After 25 minutes, pull the pan out of the oven and place the sausage links on top. Top with the cherry tomatoes. Place the pan back in the oven.
Roast for an additional 20 minutes or until the tomatoes have blistered. Remove the pan from the oven.
Serve the roasted chicken sausage with mustard potatoes immediately. Garnish with fresh parsley and enjoy!