In a large 12" skillet or saucepan, heat 1 Tablespoon oil over medium high heat. Add sausage and cook, breaking it into pieces, stirring occasionally, until browned and cooked through. Remove from pan with a slotted spoon and transfer to a medium bowl. Cover and set aside.
3 Tablespoons extra-virgin olive oil, 1/2 pound Italian sausage
In the same pan, add another 1 Tablespoon olive oil over medium high heat, and carefully arrange brussels sprouts cut side down in an even layer. Season with salt and pepper, and scatter lemon zest across the top. Let cook without stirring for 3-5 minutes, until brussels sprouts are browned underneath.
1 pound brussels sprouts, 3 Tablespoons extra-virgin olive oil, Kosher salt and black pepper, 1 lemon
Add garlic and red pepper flake (if using). Stir and cook until brussels sprouts are tender, about 2 minutes. Transfer to the bowl with cooked sausage, re-cover and set aside.
1 teaspoon garlic, 1/4 teaspoon crushed red pepper flakes
In the same pan, add another 1 Tablespoon olive oil over medium high heat. Being sure to break up any of the gnocchi that might be stuck together, add them to the pan in an even layer. Cover the pan and let cook until golden brown on the bottoms, about 2-3 minutes. Add butter and stir to coat.