Preheat oven to 375° F and grease a casserole dish.
Chop bell pepper and onion.
In a skillet over medium heat, add some oil to the pan. Once hot, add bell pepper and onion. Cook for about 7 minutes until both begin to soften, stirring occasionally.
While the bell pepper and onion are cooking down, slice kielbasa into rounds.
In a large mixing bowl, whisk together eggs. Add sausage to the bowl, and once bell pepper and onion have softened add to bowl as well. Season with a big pinch of salt and pepper. And stir it all together.
Dump everything into your casserole dish. Give it a stir as needed and transfer to the oven.
Bake for about 30 minutes until eggs are set in the middle.
Let cool for about 5 minutes, slice and serve. Enjoy!