Preheat your oven to 350°F.
In large skillet, heat oil over medium heat until shimmering. Add onion and bell pepper and cook until translucent and tender, about 5 minutes. Remove from pan and set aside.
To pan, add sausage and break up with a wooden spoon. Cook until no longer pink and sausage is cooked through. Drain and set aside.
Prepare hash browns according to package, adding 1 teaspoon of salt and 1 teaspoon of pepper.
Stir together onion and pepper, sausage, hash browns, and cheese. Pour into a 13X9-inch pan that has been lightly greased.
In medium bowl whisk together eggs, milk, and the remaining teaspoon of salt. Pour over potato mixture evenly.
Bake until a fork can be inserted and taken out clean, about 35-40 minutes. Top with chives before serving.